CSC101: Complete Cheat Sheet

A concise summary of key concepts in computer networks, internet technologies, and web markup.

1. Computer Network Fundamentals

  • Network A collection of connected computers and devices for communication and data exchange.
  • Protocol A set of rules governing data transmission (e.g., TCP/IP, HTTP).
  • Network Topologies The physical layout of a network. Common types: Bus, Star, Ring, Mesh.
  • Network Types LAN (Local Area Network): Small area (e.g., office, home).
    WAN (Wide Area Network): Large area (e.g., city, country), connects LANs.
  • Network Architectures Client-Server: A central server provides resources to client devices.
    Peer-to-Peer (P2P): All devices are equal and can act as both client and server.
  • OSI Model (7 Layers) A conceptual framework for network functions: Application, Presentation, Session, Transport, Network, Data Link, Physical.

2. The Internet and World Wide Web (WWW)

  • Internet vs. WWW
    Feature Internet World Wide Web (WWW)
    Nature Hardware Infrastructure (cables, routers, servers) Software Service (a collection of web pages)
    Protocol TCP/IP (Transmission Control/Internet Protocol) HTTP/HTTPS (HyperText Transfer Protocol)
  • Key Web Technologies URL (Uniform Resource Locator): The address of a web resource.
    HTTP/HTTPS: Protocol for transferring web pages.
    HTML (HyperText Markup Language): Language for creating web pages.
  • Online Security Steps Use strong passwords, install antivirus, use VPN/private browsing, check for HTTPS, log out of accounts, and avoid unknown downloads.

3. Markup Languages & HTML

  • Markup Language A language that uses tags to annotate a document, defining its structure and presentation (e.g., HTML, XML).
  • Essential HTML Tags <!DOCTYPE html>: Defines the document type.
    <html>: The root element of an HTML page.
    <head>: Contains meta-information (title, styles).
    <body>: Contains the visible page content.
    <h1> to <h6>: Headings.
    <p>: Paragraph.
    <a href="url">: Anchor tag for hyperlinks.
    <img src="image.jpg" alt="text">: Image tag.
    <ul> (Unordered List) & <ol> (Ordered List) with <li> (List Item).
    <table>, <tr> (row), <th> (header), <td> (cell): For tabular data.
  • Logical vs. Physical Tags Logical (Semantic) Tags: Describe the *meaning* of the content. Best practice. (e.g., <strong> for important text, <em> for emphasized text).
    Physical (Presentational) Tags: Describe the *appearance* of the content. Avoid in modern web design; use CSS instead. (e.g., <b> for bold, <i> for italic).