compression encryption and hasjing

What is compression?

Compression is the process of reducing the size of a file so it takes less storage space or can be sent faster.

What is lossless compression?

Lossless compression reduces file size without losing any data, so the original file can be recreated exactly.

What is lossy compression?

Lossy compression reduces file size by removing some data permanently, usually data that is less noticeable.

What is run-length encoding (RLE)?

A lossless compression method that stores repeated data as one value and a count.

What is dictionary coding?

A lossless compression method where repeated patterns are stored once in a dictionary and then referred to by shorter codes.

What is encryption?

Encryption is the process of scrambling data so only authorised users can read it.

What is plaintext?

Plaintext is readable, original data before encryption.

What is ciphertext?

Ciphertext is encrypted data that cannot be understood without a key.

What is a key in encryption?

A key is a value used by an encryption algorithm to encrypt or decrypt data.

What is symmetric encryption?

Symmetric encryption uses the same key for encryption and decryption.

What is asymmetric encryption?

Asymmetric encryption uses two different keys: a public key and a private key.

What is a public key?

A public key is a key that can be shared openly and is used to encrypt data.

What is a private key?

A private key is a key that is kept secret and is used to decrypt data.

What is hashing?

Hashing is the process of using an algorithm to turn data into a fixed-length hash value.

What is a hash value or digest?

The hash value is the fixed-length output produced by a hashing algorithm.

What is salt in hashing?

A salt is a random value added before hashing to make password hashes harder to crack.

What is a database?

A database is an organised collection of related data.

What is a DBMS (Database Management System)?

A DBMS is software used to create, manage, and query a database.

What is an entity in a database?

An entity is a real-world object or thing the database stores data about.

What is an attribute in a database?

An attribute is a property or characteristic of an entity.

What is a table in a database?

A table stores data in rows and columns.

What is a record in a database?

A record is a row in a table, containing all the data about one item.

What is a field in a database?

A field is a column in a table, storing one type of data.

What is a primary key?

A primary key is a field that uniquely identifies each record in a table.

What is a foreign key?

A foreign key is a field in one table that links to the primary key in another table.

What is normalisation in databases?

Normalisation is the process of structuring a database to reduce duplication and improve consistency.

What is First Normal Form (1NF)?

A table is in 1NF if it has no repeating groups and each field contains one value only.

What is Second Normal Form (2NF)?

A table is in 2NF if it is in 1NF and non-key attributes depend on the whole primary key.

What is Third Normal Form (3NF)?

A table is in 3NF if it is in 2NF and non-key attributes do not depend on other non-key attributes.

What does SQL stand for?

SQL is a language used to query and manipulate databases.

What does the SELECT command do in SQL?

SELECT is used to retrieve data from a database.

What does the FROM clause do in SQL?

FROM tells the DBMS which table to get the data from.

What does the WHERE clause do in SQL?

WHERE is used to filter records using a condition.

What does the ORDER BY clause do in SQL?

ORDER BY sorts the returned data.

What is transaction processing?

Transaction processing is handling a set of database operations as one complete unit of work.

What does ACID stand for in database transactions?

ACID stands for Atomicity, Consistency, Isolation, and Durability in transaction processing.

What is a network?

A network is two or more devices connected so they can communicate and share resources.

What is a LAN?

A LAN is a Local Area Network, covering a small geographical area such as one building or school.

What is a WAN?

A WAN is a Wide Area Network, covering a large geographical area.

What is a NIC?

A Network Interface Card is hardware that allows a device to connect to a network.

What is a MAC address?

A MAC address is a unique hardware address assigned to a network interface.

What is an IP address?

An IP address is a logical address used to identify a device on a network.

What is a packet?

A packet is a small chunk of data sent across a network.

What is packet switching?

Packet switching is when data is split into packets and sent separately across a network, then reassembled at the destination.

What is a protocol in networking?

A protocol is a set of rules for communication between devices.

What does TCP/IP stand for?

TCP/IP is the protocol suite used on the internet, where IP handles addressing and routing while TCP handles reliable delivery.

What does HTTP stand for?

HTTP is a protocol used to transfer web pages and web data.

What does HTTPS stand for?

HTTPS is HTTP with encryption for secure communication.

What does FTP stand for?

FTP is a protocol used to transfer files between computers.

What does SMTP stand for?

SMTP is a protocol used to send emails.

What does IMAP stand for?

IMAP is a protocol used to access and manage email on a mail server.

What does a router do?

A router forwards packets between different networks.

What does a switch do?

A switch connects devices within the same network and forwards data to the correct device.

What does DNS stand for?

DNS converts a domain name into an IP address.

What is a client-server network?

In a client-server network, clients request services and servers provide them.

What is a peer-to-peer network?

In a peer-to-peer network, devices act as equals and can share resources directly.

What is star topology?

A star topology connects all devices to a central device such as a switch.

What is bus topology?

A bus topology connects devices along one main cable.

What is mesh topology?

A mesh topology has devices connected to many or all other devices.

What is a web browser?

A web browser is software that requests, receives, and displays web pages.

What is a web server?

A web server is a computer or software that stores and sends web pages to clients.

What is dictionary coding?

A lossless compression method where repeated patterns are stored once in a dictionary and then referred to by shorter codes.

What is encryption?

Encryption is the process of scrambling data so only authorised users can read it.

What is plaintext?

Plaintext is readable, original data before encryption.

What is ciphertext?

Ciphertext is encrypted data that cannot be understood without a key.

What is a key in encryption?

A key is a value used by an encryption algorithm to encrypt or decrypt data.

What is symmetric encryption?

Symmetric encryption uses the same key for encryption and decryption.

What is asymmetric encryption?

Asymmetric encryption uses two different keys: a public key and a private key.

What is a public key?

A public key is a key that can be shared openly and is used to encrypt data.

What is a private key?

A private key is a key that is kept secret and is used to decrypt data.

What is hashing?

Hashing is the process of using an algorithm to turn data into a fixed-length hash value.

What is a hash value or digest?

The hash value is the fixed-length output produced by a hashing algorithm.

What is salt in hashing?

A salt is a random value added before hashing to make password hashes harder to crack.

What is a database?

A database is an organised collection of related data.

What is a DBMS (Database Management System)?

A DBMS is software used to create, manage, and query a database.

What is an entity in a database?

An entity is a real-world object or thing the database stores data about.

What is an attribute in a database?

An attribute is a property or characteristic of an entity.

What is a table in a database?

A table stores data in rows and columns.

What is a record in a database?

A record is a row in a table, containing all the data about one item.

What is a field in a database?

A field is a column in a table, storing one type of data.

What is a primary key?

A primary key is a field that uniquely identifies each record in a table.

What is a foreign key?

A foreign key is a field in one table that links to the primary key in another table.

What is normalisation in databases?

Normalisation is the process of structuring a database to reduce duplication and improve consistency.

What is First Normal Form (1NF)?

A table is in 1NF if it has no repeating groups and each field contains one value only.

What is Second Normal Form (2NF)?

A table is in 2NF if it is in 1NF and non-key attributes depend on the whole primary key.

What is Third Normal Form (3NF)?

A table is in 3NF if it is in 2NF and non-key attributes do not depend on other non-key attributes.

What does SQL stand for?

SQL is a language used to query and manipulate databases.

What does the SELECT command do in SQL?

SELECT is used to retrieve data from a database.

What does the FROM clause do in SQL?

FROM tells the DBMS which table to get the data from.

What does the WHERE clause do in SQL?

WHERE is used to filter records using a condition.

What does the ORDER BY clause do in SQL?

ORDER BY sorts the returned data.

What is transaction processing?

Transaction processing is handling a set of database operations as one complete unit of work.

What does ACID stand for in database transactions?

ACID stands for Atomicity, Consistency, Isolation, and Durability in transaction processing.

What is a network?

A network is two or more devices connected so they can communicate and share resources.

What is a LAN?

A LAN is a Local Area Network, covering a small geographical area such as one building or school.

What is a WAN?

A WAN is a Wide Area Network, covering a large geographical area.

What is a NIC?

A Network Interface Card is hardware that allows a device to connect to a network.

What is a MAC address?

A MAC address is a unique hardware address assigned to a network interface.

What is an IP address?

An IP address is a logical address used to identify a device on a network.

What is a packet?

A packet is a small chunk of data sent across a network.