Asexuals are persons who experience little or no sexual attraction. Even though they do not desire sexual relations, they still have emotional needs & are quite capable of forming meaningful relationships that are romantic & express intimacy. 

For more information about Asexuality, I would suggest checking out the Asexual Visibility and Education Network /aka/ AVEN

In 2010, AVEN held an online contest to find a flag that would represent the Asexual community.  The winning flag consisted of four stripes:

Black, which represents Asexuality. White, which represents allies and nonsexual partners who give the asexual community support. Grey, which represents grey-asexuality, meaning those identifying an unknown part out of the main asexual types. The grey also represents demi-sexuality, those feeling sexually attracted only to the person they love or have a romantic bond with.  Purple represents the Asexual community as a whole. 

Sources: The Asexual Visibility and Education Network | asexuality.org and Flagwix.com