theory 1

The Internet

A global network of interconnected computer networks spanning the entire world, representing the physical infrastructure (cables, routers, and protocols).

World Wide Web (WWW)

A graphical user interface and information system composed of websites, pages, and links that runs as a service on top of the Internet.

ARPANET (1969)

The US military research project connecting four universities from which the Internet originally evolved.

Tim Berners-Lee (1989)

The inventor of the World Wide Web at CERN.

NSFnet commercial restriction removal

The policy change in the early 1990s that allowed private businesses to connect to the Internet, driving exponential commercial growth.

Mosaic Browser

The first widely adopted graphical browser, developed at NCSA, which catalyzed the commercialization of the Web.

DNS Lookup

The first phase of a Web transaction where a browser asks a DNS server to translate a domain name into an IP address.

HTTP Request

The second phase of a Web transaction where the browser sends a request message to the server asking for the website files.

Server Response

The third phase of a Web transaction where the server replies with a status code (such as 200 OK) and sends HTML, CSS, JS, and images.

Rendering

The final phase of a Web transaction where the browser assembles all retrieved files into the complete webpage the user interacts with.

Web Client (The Requester)

A computer running browser software that is connected to the Internet only when needed and uses HTTP to request assets.

Web Server (The Responder)

A computer continually connected to the Internet running server software to receive requests and send resources.

HTTP Protocol

The fundamental communications protocol of data exchange on the Web.

SMTP (Simple Mail Transfer Protocol)

An Internet protocol dedicated strictly to sending email messages between servers.

POP (Post Office Protocol)

An Internet protocol used for receiving email by downloading messages to a local client and typically deleting them from the server.

IMAP (Internet Message Access Protocol)

An Internet protocol used for receiving email by keeping messages synced dynamically on the server.

FTP (File Transfer Protocol)

A protocol used to exchange raw files between computers that operates completely independently of web browsers and HTML.

URL (Uniform Resource Locator)

The complete address of a resource on the Internet, consisting of a protocol, domain name, and file path.

Domain Name

An organization identifier that locates an entity on the Internet and maps to a unique numeric IP address.

HTML (High-Level Analogy)

The structure of a webpage, defining what "is" on the page (analogous to the walls, rooms, and foundation of a house).

CSS (High-Level Analogy)

The visual style of a webpage, defining how it looks (analogous to the paint, furniture, and lighting of a house).

JavaScript (High-Level Analogy)

The behavior of a webpage, defining how it behaves (analogous to the utilities, electricity, and plumbing of a house).

Universal Design

The design concept that websites must be structured to be usable by all people, of all abilities.

Universal Design Legal Mandate

A legal requirement making website accessibility mandatory for government and educational institutions.

Consistency Principle in Web Design

The practice of presenting recurring features (such as navigation bars, headings, and logos) in the same place to make a site easier to navigate.

Early HTML Layout Limitation

The historical use of table elements for page layout, which was cumbersome and difficult to maintain.

Mixed Content and Presentation Limitation

An early HTML issue where styling within HTML (using inline styles or font tags) mixed structural content with visual presentation.

Static Structure Limitation of HTML

The limitation where HTML alone can only create static structures and cannot respond dynamically to user actions without JavaScript.