Google Knol is a free platform for writers by google. Share your knowledge on any niche topic and at the same time earn Google Ad Revenue. Each write up that you publish is known as a knol. You can publish any number of knols on any niche topics of your interest.
If you have a gmail account you can sign up on Google Knol with this account or create a new one. It is recommended that you do write up on topics that you have great knowledge about or topics that is of interest to you. You can share pictures and upload videos from google and youtube in your article.
As Knol being a project of google, they get a lot of visitors everyday from around the world . Thus it is a good platform for writers to build up their career with google on knol.