seedwiki is a wiki farm where anyone can host a non-commerical wiki. You cannot host a wiki that is pornographic or that advocates violence. Basic wikis are free, but they will be removed if they have no editing activity after 90 days. For a small fee you can add advanced features to your free wiki.
Search engines have turned the web into a powerful surveillance mechanism. Seedwiki hides wikis from search engines by default. If you want the content of your wiki to be indexed by search engines you will have to change the settings in its control panel. If you are a teacher who has a class posting on a wiki I encourage you to not open it up to the search engines. Your students will thank you in later years when they apply for jobs in companies whose HR departments routinely search the web for their applicants.