You can't trust everything you see on the internet. But can you trust anything you see on the internet?
It can be difficult to know what to believe and what to ignore when anyone could theoretically make up anything. If you care enough about a claim you can, of course, research it thoroughly, but that seems like quite an investment of time, especially when we all encounter so many claims and stories every single day.
Fortunately, it is possible to do some simple digging to investigate any given claim without having devote very much time at all. The process for this is covered in the two and a half to three hour online curriculum Check, Please!. Even if you don't have enough time to go through all of it, just working through the first lesson will give you a good introduction to media literacy and becoming an informed consumer.