Introduction to Web Technologies

Internet

  • Global network of interconnected computers using the TCP/IP protocol suite.

  • Devices identified by IP addresses in dotted-decimal form n.n.n.n with each n \in 0-255 (e.g., 1.2.3.4 \leftrightarrow 5.6.7.8).

World Wide Web (WWW)

  • Often called the “Web”, is one of the mostly commonly used services on the internet.

  • Uses the HTTP(Hypertext Transfer Protocol) to transmit data.

  • Invented by Tim Berners-Lee at CERN in 1989.

  • Transfers hypertext documents via HTTP.

  • Other Internet services use different protocols (e.g., SMTP for e-mail).

Webpage – serves as a storage of Web Information.

Website – collection of webpages linked together to have a common goal.

Web browser – a software application for presenting and traversing information on the Web.

Web server – host that stores and serves webpages; common software: Apache, IIS, NGINX, GWS.

  • URL (Uniform Resource Locator) – is a reference used to specify addresses on the WWW.

     Example: https://manuelgarcia.info/feu/it0043.html

>https – protocol (secure HTTP).

>manuelgarcia.info – domain name.

>.info – top-level domain (TLD).

>/feu/ – subdirectory on the server.

>it0043.html – specific HTML file (webpage).

  • HTML (HyperText Markup Language) – standard language for creating webpages and web applications.

How the Web Works

  • Browser converts URL into an HTTP request.

  • DNS translates the domain to a server IP address.

  • Browser sends request to the web server.

  • Server returns an HTTP response (HTML/CSS/JS, media, etc.).

  • Browser renders response; additional resources are fetched as needed.

Web Development Areas

  • Front-End (client side): presentation & interactivity using {HTML5,\;CSS3,\;JavaScript}.

  • Back-End (server side): business logic, data processing, server configuration; languages such as PHP, Ruby, Python, Node.js.

  • Database / Query Language: SQL variants (MySQL, Oracle) manage persistent data.

Essential Languages to Learn

  • Markup: HTML5.

  • Styling: CSS3.

  • Client-side scripting: JavaScript + modern frameworks (React, Angular, Vue).

  • Server-side scripting: PHP, Ruby, Python, Node.js, etc.

  • Query language: SQL (MySQL, Oracle, PostgreSQL, etc.).