mailto (colon) (no slashes after the colon) is one in which you type anyone's e-mail address after the colon. After you type mailto: followed by the address (protocols have no spaces), you press enter and Outlook, Outlook Express or whatever your main e-mail system is will pop up. The address you typed in in the URL will appear in the "address" bar. If you want to, after you type mailto, the colon and the URL, you can type a question mark, then the word "subject", an equals sign, and a subject (with no spaces), and all spaces replaced by %20 (the hex code for a space.
Also, there is an ftp (colon) // (slashes needed) protocol. Just that instead of accessing the Web, it accesses file transfer protocol (FTP). You can also type in a user name, an at sign, and the URL of the FTP server after the ftp (colon) // protocol.
The news (colon) protocol (without slashes) accesses a newsgroup, in which people can join discussions. For example, a popular non-Web Internet site, in this case a newsgroup, is alt.tv.startrek. If you wanted to visit the site, in the address bar, you would type:
news, then a colon, then type alt.tv.startrek
and it would open the connection wizard, in which you set it up and you can access the newsgroup server.
The file (colon) // (slashes required) URL is good for accessing individual files. It has the ability to access the machine you're using, or one you're connected to, just by typing the path, in which you do file (colon) // then another slash (making 3), then in which you type a folder name, another slash, a folder inside that, and so on, until the file name. Hit enter, and the file is accessed.
You can also have a telnet (colon) // (slashes required) protocol. It follows the format of FTP protocols. You can do your username, at sign, and the server name. It will ask you for your password. To speed things up, do username, a colon, password, at sign and site name.
There is an NNTP (colon) // protocol out. When used, you type in the name of a Website that has newsgroups available. After the slash, instead of a directory, you type in the newsgroup name.