The Forest Stewardship Council is a non-profit organization founded in 1993. Their stated goal is to encourage the practice of sustainable forestry. They issue certifications to forests managed according to their standards, and products made from wood grown under these standards. Environmentally conscious people can choose to look for these products, encouraging corporations to adhere to these standards. This basic information is available on Wikipedia and the web site of the Forest Stewardship Council.
This is from the list of frequently asked questions on their website:
Only FSC
* prohibits conversion of natural forests or other habitat around the world
* prohibits the use of highly hazardous pesticides around the world
* prohibits the cultivation of genetically modified trees (GMOs)
* respects the right of indigenous peoples around the world
* controls each certified operation at least once a year – and if they are found not to comply, the certificate is withdrawn
They have some critics in the environmental movement. Sourcewatch has a page devoted to them. The World Rainforest Movement has suggested they are much too soft on the companies they watch, and that their actions are sometimes counterproductive. These accusations are detailed in a book called Certifying the Uncertifiable.
There is currently no major competitor to the FSC. Certifying the Uncertifiable calls for them to revoke certain certifications rather than encouraging people to follow the ratings of a different organization.