The Single has now evolved into a multi-purpose marketing tool, giving musicians the opportunity to offer different styles of 'singles' to their fans for a variety of different outcomes.

The following is a look at the most popularly used varieties of singles, and how musicians can best use them to their advantage:

1) Radio Single: Released to captivate a larger audience, the Radio Single is typically shorter in length (around 3 minutes) and is more so about creating a strong memorable hook than showing off musicianship skills. In the end, if this song can stay with someone after it has finished, it has done its job.

The radio single is one that every band should include on their demo and/ or use as the focus of their Press Kit/ EPK.

2) The Street Single: While the Radio Single is used to expand a fan base, the purpose of the Street Single is to satisfy existing fans. These singles are typically seen as a 'deep cut', or a track that is less about a pop hook and more about getting down to business, showing off both musicianship skills and raw talent.

If you have the skills to be able to take a serious, extended solo, or have some racy lyrics that really hit home, this is format to give your fans what they love about you and your music.

3) iTunes Bonus Single: This exclusive single is a sales driver, plain and simple. Many times, the iTunes Bonus Single can be an extended, live track, an alternate version of a song that appears on the album, or even a song that was previously unreleased.

The idea here is to offer your fans something valuable enough that it makes the album worth buying. It can be the tipping point for many fans who are on the fence about making a purchase.

4) Free Download Single: The Free Download Single can be used quite a few different ways. In any situation, these 'free' downloads, should be leveraged by musicians as an incentive for fan support or involvement. Many times, Free Downloads are offered as a reward for joining a mailing list or for pre-ordering an album, though through services like Tweet-for-a-Track and CashMusic, musicians can offer fans a Free Download in exchange for sharing the opportunity with their friends and followers on their own social networking accounts.

5) Leaked Single: Now known as 'the way to receive huge internet buzz', the Leaked Single is one that is 'accidentally' released in hopes that the satisfaction fans receive by obtaining something they are not supposed to have will make them giddy with anticipation.

If artists are planning on 'leaking' a track, time and attention needs to be paid so that it not only seems the track was actually accidentally leaked and not just released, but also so that the music gets into the right hands of influential bloggers and super fans who's announcement of the leaked track will help is spread. But be careful, if it comes out that you were behind the leak, the inauthentic nature could leave a sour taste in the mouths of fans.

Note: I do not condone dishonesty between artists and fans, but if you can make this work, it does have very powerful benefits.

6) Viral Video Single: The Viral Video Single is one that is either unbelievable original or outrageously racy, and no matter how you plan for it, there is really no guarantee you can make something go 'viral'. The benefit of course, if you can manage to pull this off, is that videos are one of, if not THE most easily sharable format on the internet. When a video goes viral, it can be found on any and every reputable online source, from websites and blogs to twitter and Facebook (and of course youtube).

7) Remix Single: There are two very important reasons for considering to remix one of your songs: It allows you to revisit a previously popular song and it allows you to connect with both blogs and fans of a genre that you are not typically associated with.

There is also the idea of becoming the remix-er by creating your own remixed version of someone else's song. This is a popular method in the realm of hip-hop. Again the opportunity here is to connect with the fans of another artist or genre who may not necessarily have heard of you or your music.