Use of the Tumblr blogging service is free, provided you abide by the community guidelines. The guidelines are in place to protect other Tumblr users and the service. If your blog is found to be in violation of the terms of service or community guidelines, you may be notified via email to explain or correct the transgressions. If you ignore these notifications, your Tumblr account may be suspended and your IP address may be blocked. Depending on the severity of the infringement, Tumblr reserves the right to terminate your account without any notice.
Tumblr does not penalize you for posting adult content -- provided that you flag your blog as "not safe for work." The NSFW flag is activated from the settings page of your Tumblr dashboard and prevents your blog from appearing in the search results of people who do not want to view adult content. You are not allowed to upload any sexually explicit videos using the Tumblr upload video feature or display media that showcases gore.
You can use Tumblr to promote your website or business provided that you do not engage in spam or use deceptive methods to gain more Web traffic. Practices such as using misleading tags for your posts or posting links that lead to a different page than advertised can lead to the termination of your account. It is also a violation of the community guidelines to post nothing but automated content or impersonate another person, brand or company using your Tumblr blog.
Tumblr has very strict copyright rules that state you are not allowed to post any content that you are not authorized to use on your blog. Exceptions are made for content that adheres to the fair use principle, but be careful about using copyrighted or trademarked material. You are also not allowed to use your Tumblr blog to promote or engage in illegal activities, such as posting download links to copyrighted material.
You are not allowed to use your Tumblr blog to promote any type of violence or prejudice against anyone on the basis of their sexual orientation, race, religion or ethnic origin. Tumblr supports freedom of speech, but will take down material that is deemed as malicious bigotry. If you persist in posting such material, your account will be suspended. You may not use the Tumblr platform to harass other users by threatening them, sending unwanted messages or stalking them. Bullying minors is also a violation of the community guidelines.