Comptia A+ Core 1

LCD panel types

TN

IPS

VA

OLED

TN (Twisted Nematic)

the fastest response time of any LCD panel type and the cheapest to manufacture. Poor color accuracy and very bad viewing angles. Best suited for fast gaming where speed is more important than color quality.

IPS (In-Plane Switching)

has the best color accuracy and the widest viewing angles of any LCD type. Slightly slower response time than TN. More expensive. Best for photo editing, video work, and general productivity.

VA (Vertical Alignment)

has the best contrast ratio of any LCD panel type, meaning deeper blacks than IPS or TN. Middle ground between IPS and TN in most other ways. Prone to motion blur. Good for watching movies and media consumption.

OLED (Organic Light Emitting Diode)

each individual pixel produces its own light, so pixels that display black are completely turned off. Achieves true blacks and infinite contrast. Very thin, vivid color, and power efficient when displaying dark content. Risk of burn-in if a static image is displayed for too long. More expensive than LCD types.

Backlight Types

CCFL (Cold Cathode Fluorescent Lamp)

LED

Mini-LED

CCFL (Cold Cathode Fluorescent Lamp)

the older backlight technology used in laptops before LED. A fluorescent tube that requires an inverter board to function. If a laptop screen is very dim but an image is faintly visible when you shine a flashlight at it at an angle, the CCFL lamp or inverter has failed.

LED

the modern standard for laptop and monitor backlighting. Uses light-emitting diodes instead of fluorescent lamps. Does not require an inverter board. Thinner, lighter, and more power efficient than CCFL. Failure causes the screen to go completely dark.

Inverter Board

a small circuit board found only in laptops with only with CCFL backlights. Converts DC power from the motherboard to the AC power that the CCFL lamp requires. Failure symptoms are a dim screen, flickering, or a high-pitched buzzing sound coming from the display area. Not present in any LED-backlit laptop.

Digitizer

Transparent layer on top of the LCD that detects touch input - found in touchscreen laptops and tablets - can sometimes be replaced separately from the LCD

Mini-LED

a newer backlighting technology that places thousands of very small LEDs behind an LCD panel in separate dimming zones. Provides much better contrast and local dimming than standard LED backlighting while avoiding OLED burn-in risk.

DC Jack

Port where the AC adapter plugs into a laptop - common failure point from physical stress - symptoms include battery not charging or laptop only working at certain angles

Laptop Battery Types

Li-Ion (Lithium Ion) and Li-Po (Lithium Polymer) - rated in mAh or Wh - never dispose in regular trash - recycle at certified facilities

Li-Ion Battery (Lithium Ion)

the most common laptop battery chemistry. Rated in milliamp-hours or watt-hours. Does not have a memory effect so it does not need to be fully discharged before recharging. Must never be thrown in regular trash and must be taken to a certified recycling facility.

Li-Po Battery (Lithium Polymer)

similar electrochemistry to Li-Ion but uses a polymer electrolyte instead of liquid. Can be made thinner and in more flexible shapes. Used in ultrabooks and mobile devices where a thin profile is important. Same recycling requirements as Li-Ion.

SO-DIMM (Small Outline Dual Inline Memory Module)

the RAM form factor used in laptops. Physically about half the length of a full desktop DIMM. Current versions are DDR4 SO-DIMM with 260 pins at 1.2V and DDR5 SO-DIMM with 262 pins at 1.1V. Many modern ultrabooks have RAM soldered directly to the motherboard and cannot be upgraded after purchase.

Laptop Storage Options

2.5-inch SATA HDD or SSD - M.2 SSD using either SATA or NVMe protocol - M.2 is the modern standard

Wi-Fi Antenna Wires

routed inside the display lid and around the bezel of a laptop. Run through the hinge assembly and connect down to the wireless card installed in the base of the laptop. These wires must always be reconnected and routed correctly when reassembling a laptop display.

Webcam

integrated into the top of the display bezel. Connects to the motherboard via a small internal USB cable. Failure typically requires replacing the full bezel assembly rather than just the camera module.

2.5-inch SATA Storage

the traditional laptop hard drive or SSD form factor. Uses the SATA III interface which maxes out at about 550 MB/s in real world use. Being replaced by M.2 in most modern laptops but still common in budget devices.

M.2 SSD

a small PCB-style solid state drive that slots directly into the motherboard. The most common size is 2280 meaning 22mm wide by 80mm long. Can use either SATA protocol limited to about 550 MB/s or NVMe protocol over PCIe which reaches up to 3500 MB/s on PCIe 3.0 and 7000 MB/s on PCIe 4.0. The two are not interchangeable in all slots.

NVMe (Non-Volatile Memory Express)

a storage protocol designed specifically for flash-based SSDs. Communicates directly over PCIe lanes rather than going through the older SATA bus. Dramatically lower latency and much higher throughput than any SATA-based drive. PCIe 3.0 NVMe reaches about 3500 MB/s read, PCIe 4.0 reaches about 7000 MB/s.

Keyboard

most laptop keyboards are replaceable by removing screws from the bottom panel or releasing retention clips under the display bezel. Some ultrabooks use keyboards that are permanently attached and cannot be replaced without replacing the entire top case assembly.

Touchpad

a capacitive touch surface built into the laptop palm rest used as a pointing device. Can typically be disabled via a function key combination or through Device Manager in Windows. Some high-end laptops use glass touchpads with better tracking accuracy.

Wireless Card

handles both Wi-Fi and Bluetooth in a single combination card. Installed in a Mini PCIe or M.2 A/E-key slot inside the laptop. The antenna wires from the display lid connect to this card. Replacing it also requires reconnecting those antenna wires.

Thermal Paste

a thermally conductive compound applied between the CPU integrated heat spreader and the base of the heatsink. Fills microscopic surface imperfections to eliminate air gaps that would otherwise block heat transfer. Must be cleaned off and reapplied every time a heatsink is removed and reinstalled because old paste dries out and loses its effectiveness.

ExpressCard

a legacy laptop expansion slot available in 34mm and 54mm widths. Allowed adding functionality like eSATA ports, USB 3.0, or cellular modems. Replaced in modern laptops by USB-C and Thunderbolt docks. Still seen on some older enterprise laptops.

USB-C

the modern universal connector used on Android phones, iPad Pro, iPad Air, and most current laptops. A small oval-shaped reversible connector that supports data transfer, video output via DisplayPort Alt Mode, and charging all in one port. The connector shape alone does not indicate the speed or capability of the port.

Thunderbolt 3

uses the USB-C physical connector and provides 40 Gbps bandwidth. Supports PCIe tunneling, DisplayPort video output, and USB Power Delivery charging. Backward compatible with USB-C devices at lower speeds.

Thunderbolt 4

same 40 Gbps speed as Thunderbolt 3 but with stricter certification requirements. Must support two 4K displays or one 8K display, minimum 32 Gbps PCIe bandwidth, and at least 15W charging on all ports.

Lightning Port

Apple’s proprietary connector used on iPhones and iPads manufactured before the switch to USB-C. Supports data sync and charging. Being phased out across Apple’s product line following EU regulations requiring USB-C.

Micro-USB

an older small USB connector used on Android devices and accessories before the industry transitioned to USB-C. Still found on some budget devices, older accessories, and charging cables. Supports USB 2.0 speeds.

Mini-USB

a very old connector found on older cameras, early smartphones, and some older accessories. Rarely encountered today.

Qi Wireless Charging

an inductive wireless charging standard used by most modern smartphones. Requires placing the device on a compatible charging pad. Standard Qi provides 5 to 15 watts. Apple MagSafe uses a ring of magnets to precisely align the phone on the pad while also using Qi induction for power delivery.

NFC (Near Field Communication)

operates at a maximum range of about 4 centimeters. Used for tap-to-pay transactions through services like Apple Pay and Google Pay, contactless transit cards, and quick device pairing. Very low bandwidth but requires no manual configuration or password.

Bluetooth

a short-range wireless protocol used for peripherals, audio devices, and accessories. Bluetooth 4.x BLE (Bluetooth Low Energy) operates at about 10 meters at 1 Mbps and is optimized for battery-powered sensors and wearables. Bluetooth 5.x extends range to about 40 meters at 2 Mbps and is better for audio peripherals and general accessories.

Wi-Fi Calling

Allows voice calls over Wi-Fi instead of cellular - useful in areas with poor cellular signal strength

Bluetooth Pairing

involves enabling Bluetooth on both devices, putting the target device into pairing or discoverable mode, selecting it from the list of discovered devices, and confirming a PIN or passkey if prompted. Once paired, devices reconnect automatically when in range and both have Bluetooth enabled.

Infrared (IR)

a line-of-sight wireless communication method used on some mobile devices to act as a remote control for televisions and other appliances. Very limited range and requires the devices to be pointed at each other. Being phased out on modern phones.

Zigbee

a wireless IoT communication protocol used in home automation devices such as smart bulbs, sensors, and locks. Operates at 2.4 GHz at 250 Kbps with a range of 10 to 100 meters. Can form mesh networks where devices relay signals to extend range. Can interfere with 2.4 GHz Wi-Fi.

Z-wave

a wireless IoT home automation protocol that operates at sub-1 GHz frequency, specifically around 908 MHz in the US. Range of about 30 meters at 100 Kbps. The sub-1 GHz frequency means it does not interfere with Wi-Fi or other 2.4 GHz devices. Used in smart locks, thermostats, and home security sensors.

Docking Station

a device that expands a laptop or tablet’s connectivity by providing additional ports such as USB-A, HDMI, DisplayPort, Ethernet, SD card readers, and audio jacks. Connects to the laptop via USB-C or Thunderbolt. Some provide power delivery to charge the laptop through the same cable.

Port replicator

similar to a docking station but typically duplicates the ports already on the laptop rather than adding new functionality. Less common term today as docking stations have largely replaced them.

Stylus

a pen-shaped input device used with touchscreen devices. Passive styluses work with any capacitive screen. Active styluses like Apple Pencil and Samsung S Pen have electronics inside that communicate with a specialized digitizer in the display, enabling pressure sensitivity and palm rejection.

WiFi on Mobile

configured by opening Wi-Fi settings, selecting an SSID from the list, entering the network password, and connecting. The device stores credentials and reconnects automatically when in range. Supports WPA2 and WPA3 security protocols.

Cellular Data

requires a SIM card from a carrier physically installed in the device or an eSIM configured digitally. LTE provides typical speeds of 10 to 100 Mbps. 5G Sub-6 GHz provides 100 Mbps to 1 Gbps over wider coverage areas. 5G mmWave provides multi-gigabit speeds at very short range near specific infrastructure

eSIM (Embedded SIM)

a digital SIM built into the device that can be configured remotely by a carrier without needing a physical SIM card. Allows switching carriers without physically swapping cards. Found on most recent iPhones and many Android flagships.

AirPlane Mode

disables all wireless radios simultaneously including cellular, Wi-Fi, Bluetooth, GPS, and NFC. Required during flight takeoff and landing in most jurisdictions. After enabling airplane mode, individual radios such as Wi-Fi or Bluetooth can be manually re-enabled

WiFi Calling

routes voice calls over a Wi-Fi connection instead of the cellular network. Useful when cellular signal is weak but Wi-Fi is available. Must be supported by the carrier and enabled in phone settings.

Mobile Hotspot

allows a smartphone or tablet to share its cellular data connection with other devices by creating a Wi-Fi access point. Other devices connect to the hotspot like any Wi-Fi network. Consumes the phone’s cellular data allowance. May require a specific carrier plan that includes hotspot capability.

Tethering

sharing a phone’s internet connection via USB cable, Bluetooth, or Wi-Fi hotspot to another device. USB tethering is the most reliable and fastest method and also charges the phone simultaneously.

VPN on Mobile

creates an encrypted tunnel between the device and a remote VPN server. Required for secure access to corporate networks. Can be configured manually using protocols like IKEv2, IPSec, or OpenVPN, or pushed automatically to enrolled devices via MDM.

uses a combination of GPS satellites, cellular tower triangulation, and nearby Wi-Fi network identification to determine the device’s physical location. Can be enabled or disabled globally or on a per-app basis from privacy settings. GPS is most accurate outdoors, Wi-Fi positioning works well indoors.

IMAP (Internet Message Access Protocol)

an email receiving protocol that synchronizes messages between the device and the mail server. Email stays on the server and is accessible from multiple devices. Unencrypted on port 143, encrypted with SSL/TLS on port 993. Preferred for any multi-device email use.

POP3 (Post Office Protocol 3)

an email receiving protocol that downloads messages from the server to the local device and typically deletes them from the server afterward. Designed for single-device access. Unencrypted on port 110, encrypted on port 995. Not preferred for modern use.

SMTP (Simple Mail Transfer Protocol)

the protocol used to send email. Port 25 is for server-to-server relay and is often blocked by ISPs. Port 587 with STARTTLS is the standard for email clients to submit outgoing mail. Port 465 is the legacy SSL SMTP port.

Exchange ActiveSync (EAS)

Microsoft’s mobile email protocol for corporate environments. Operates over HTTPS on port 443. Provides push email delivery so messages arrive instantly without polling. Also syncs calendar appointments, contacts, and tasks. Commonly managed and deployed via MDM.

S/MIME

a standard for encrypting and digitally signing email messages on mobile devices. Requires a digital certificate to be installed on the device. Encrypting an email ensures only the intended recipient can read it. Signing an email proves it came from the stated sender and has not been tampered with.

Mobile Data Synchronization

the process of keeping data current between a mobile device and cloud services or other devices. Data that syncs includes contacts, calendar events, email, photos, videos, documents, app settings, browser bookmarks, and health and fitness data. iCloud handles this for Apple devices. Google Account handles it for Android devices.

icloud

Apple’s cloud platform for sync and backup. Automatically syncs contacts, calendar, photos, Safari bookmarks, app data, and documents across all Apple devices signed into the same Apple ID. Provides 5 GB free storage. Backup occurs over Wi-Fi when the device is charging.

Google Accounts Sync

Android’s cloud sync service. Syncs contacts, Gmail, Calendar events, Chrome bookmarks, Drive files, and app data across all Android devices signed into the same Google account. Backup is stored to Google servers.

MDM (Mobile Device Management)

enterprise software that allows IT administrators to remotely manage mobile devices across an organization. Capabilities include enforcing screen lock and PIN complexity, requiring device encryption, pushing Wi-Fi and VPN profiles, installing or removing applications, tracking device location, and performing remote wipes.

MAM (Mobile Application Management)

manages only the corporate applications and their data on a device rather than managing the entire device. Creates a secure container for corporate apps. Corporate data can be selectively wiped without touching personal apps and data. Preferred approach for BYOD programs.

BYOD (Bring Your Own Device)

a corporate policy allowing employees to use their personal smartphones and tablets for work purposes. Requires balancing corporate data security with employee privacy. Full MDM enrollment may intrude on personal data so MAM or containerization is often the preferred management approach.

Corporate Owned Device

a device purchased and owned by the employer and issued to the employee. Full MDM enrollment is appropriate. The company retains the right to fully wipe the device. Less employee privacy concern than BYOD.

Two-Factor Authentication (2FA)

a login security method that requires two separate verification factors. Combines something you know such as a password with something you have such as an authenticator app code or SMS message. Significantly reduces the risk of account compromise even if the password is stolen.

Authenticator App

an application that generates time-based one-time passwords (TOTP) that expire every 30 seconds. Examples include Google Authenticator and Microsoft Authenticator. The codes are generated locally on the device and do not require internet access at the moment of generation. More secure than SMS-based codes because they cannot be intercepted in transit.

Remote Wipe

the ability to erase all data on a lost or stolen device remotely over the network. A full wipe erases everything and restores factory settings. A selective wipe removes only corporate data while preserving personal content. Requires the device to be enrolled in MDM or have Find My Device enabled and an internet connection.

Screen Lock and Auto-Lock

a security feature that locks the device after a defined period of inactivity. Requires a PIN, password, pattern, fingerprint, or face recognition to unlock. The timeout duration and minimum PIN complexity can be enforced through MDM policy.

Find My Device (Locator App)

a built-in feature that allows the device’s location to be tracked remotely over the internet. Called Find My on iOS and Find My Device on Android. Can also display a message on the screen, play a sound, lock the device, or trigger a remote wipe. Requires location services to be enabled and the device to have internet connectivity.

Failed Login Wipe

a security feature that automatically erases the device after a configurable number of consecutive failed authentication attempts. Prevents brute-force guessing of a PIN. The number of attempts before wipe is set through MDM policy.

Full Device Encryption

encrypts all stored data on the device so that it is unreadable without the correct authentication credentials. Enabled by default on all modern iOS devices since iOS 8 and Android devices since Android 6. Means that even if the physical storage chip is removed from the device the data cannot be read.