When you feel ready to introduce your band to media, venues where you would like to perform, a music programmer at a radio station, agents, managers, or anyone else, you’ll want to have a bio.
The objective of a bio to briefly share enough about your music and your band to invite curiosity on the part of a reader who knows nothing about you. Many people reading it may still be deciding whether they are going to listen to your music or not. A good bio will nudge them towards giving your music a listen. It is not the right forum for your life story or a dissertation on creativity. In fact, ideally it will fit on one page. Two at the most.

It should also have a picture of the band or band related artwork. Put some thought into these visuals. It should appeal to them or pique their interest. For better or worse, the people receiving your information often make quick judgments. They simply get sent too much music. Remember your task: get them to want to hear your music. It should also contain factual information such as where you are from, members of the band, a comment or two on how the band came into existence, and perhaps a mention of some of your musical influences or likes. Always be sure to include contact information such as a band contact, e-mail address, phone number, website/myspace address, and mailing address.
A press release is similar to a bio but is more incident specific, with a newsworthy announcement. For instance, you are announcing your upcoming release date, or you just were picked to open for a popular headlining act.