Many student artists publish their art on websites and social networks.
Here are the links to some popular sites' terms of service. Before you start posting content MAKE SURE YOU READ THE INTELLECTUAL PROPERTY SECTIONS or COPYRIGHT SECTIONS of the site's terms of service.
You may be giving them the right to sell your work!
In addition to these terms, many sites have specific policies concerning Coryright and what to do if you feel your copyright has been infringed upon by a third party or a user on these sites.
In this world of mass media, it is great to spread the word about your work, just be careful how you spread it.
You retain your rights to any Content you submit, post or display on or through the Services. By submitting, posting or displaying Content on or through the Services, you grant us a worldwide, non-exclusive, royalty-free license (with the right to sublicense) to use, copy, reproduce, process, adapt, modify, publish, transmit, display and distribute such Content in any and all media or distribution methods (now known or later developed).