Terms Letter: 0
.com
It is a top level domain name(TLD). Very popular one. Its primary purpose was to be used by commercial enterprises. However nowadays the .COM are the most commonly used domains.
.gif
It is a file extension used for image files. A graphics file format developed by CompuServe and used for transmitting raster images on the Internet. It is very good for use with images that has large areas of one and the same color
.htaccess
A special file used by the Apache Web Server. Using .htaccess you can configure quite a lot options of the web server itself. For example, you can: change default/start page of your site; prevent directory listing; establish password protection; prevent hotlinking; manage redirects; set some mime types; deny access by ip address or hostname.
.jpg or .jpeg
These are extensions used for image files that utilize a graphics format developed by the Joint Photographic Experts Group, hence the name. JPEG is a popular file compression format which allows the storage of high quality images in relatively small files.
.mov
Apple QuickTime MOVie motion video file format. QuickTime player is needed in order to play such a file.
.mpg or .mpeg
File extension used for movies in high quality video format developed by the Motion Pictures Expert Group, hence the name.
.zip
A compressed file format (.zip). To uncompress the file, you need a utility like WinZip (Windows). Zip files contain vast amounts of information that has undergone compression to reduce the amount of space that the data take up. In other words when you ZIP a file it gets smaller in size.
404 Page
Also known as missing page or 404 HTTP error. It is a special response defined by the HTTP protocol. The server tells the browser that the document you have requested cannot be found on the server. Usually a broken hyperling will result in 404 error. Most web hosting providers give an option to the user to modify the appearance of the 404 page or set their own HTML document to act as an 404 page.
301 Redirect
Very popular these days. If you happen to read some forum regarding search engine optimization SEO, you will most probably get on a topic for 301 redirects and search engines in particular Google. Simply the 301 redirect is an HTTP response, which tells your browser or the search engine that the URL requested has been moved permanently. There is also 302 response which means moved temporary.