Hyphens and dashes all have specific uses. They cannot be used interchangeably.
The hyphen is used to separate compound words, either a compound noun or a compound adjective modifying a noun. If there is more than one phrasal adjective modifying a single noun, hyphenation becomes especially important.
Examples: fuzzy-wuzzy bear, video-game-magazine dispute, state-inspected assistant-living facility, twenty-four hours, twenty-four-hour clock.
The hyphen is also used to separate numbers that are not inclusive, such as telephone numbers, Social Security numbers and ISBN numbers.
Example: Her telephone number is 501-324-7611.
Another use for the hyphen is to separate letters when the word is spelled out.
Example: Her name is Alayna, spelled a-l-a-y-n-a.
In URLs careful distinction needs to be made between a hyphen (-), a tilde (~), and an underline (_). Examples: http://www.rz.uni-karlsruhe.de/~szm http://www.ucsb.edu/univ_press/ . If you want people to easily find your website or your e-mail address, it is best not to use any of these three since they are easily confused.