The following list of abbreviations only scratches the surface of the jargon you will meet as you learn web design...

Asynchronous JavaScript and XML - a group of related technologies used to build the client-side portion of interactive web applications.
Active Server Pages - a Microsoft server-side scripting engine for constructing dynamic web pages.
Cascading Style Sheet - a method for describing the visual appearance, or formatting, of web pages.
Document Object Model - a method for interacting with objects in HTML, XHTML and XML documents.
Document Type Definition - a description of the components that make up a valid page of mark up, such as an HTML page.
File Transfer Protocol - a protocol used to move large files across an internet connection. For example, this method is usually used to upload a complete web site to a server.
Graphics Interchange Format - a common image format for icons, buttons etc on a web page.
Hypertext Markup Language - the language used behind the scenes to define the formatting of a web page.
Hypertext Transfer Protocol - the protocol used to transmit a we page from the server to the client's browser.
Hypertext Transfer Protocol Secure - this is a combination of the basic HTTP mechanism with the SSL/TLS protocol to give secure delivery of a web page ensuring that sensitive details, such as credit card information, cannot be seen by outsiders.
Joint Photographic Expert Group - a common file format for photo quality images.
Java Server Pages - a Java-based server-side language for constructing dyamic web pages.
MPEG Audio Layer III - this is a common form of encoding for audio files. It uses lossy compression, meaning that it is a much smaller file than the equivalent CD quality audio, but information is lost in the encoding process, and the resulting quality is potentially lower than that of an audio CD.
Moving Picture Experts Group - a common format for digitially encoding movies.
Hypertext Preprocessor - a server-side scripting language for constructing dynamic web pages.
Portable Network Graphic - a image format intended as a replacement for GIF images in web pages.
Secure Socket Layer - a method of making sure that the basic connections between computers is secure and that any information transmitted cannot be intercepted. This has now been replaced by TLS.
Scalable Vector Graphic - an XML based format for describing vector graphics.
Transport Layer Security - this is a cryptographic technique of ensuring that the connection between two computers is secure and information transmitted cannot be intercepted.
Uniform Resource Locator - essentially, this defines the address of a web page. A more detailed discussion is given here.
What You See Is What You Get - any editor that shows on screen what you expect to see when the document is finally printed or displayed on the web, while you are actually editing the document.
Extensible Hypertext Markup Language - an extended version of HTML based directly on XML.
Extensible Markup Language - a language for describing the structure of a document that is machine readable, but also easily comprehensible to humans.