Here are some items to consider that can help determine authenticity:

• Location of the poster - are they in the place they are tweeting or posting about?
• Network - who is in their network and who follows them? Do I know this account?
• Content - Can the information be corroborated from other sources?
• Contextual updates - Do they usually post or tweet on this topic? If so, what did past or updated posts say? Do they fill in more details?
• Age - What is the age of the account in question? Be wary of recently created accounts.
• Reliability - Is the source of information reliable?

There are many articles about studies on misinformation and disinformation, such as this one from the Boston Public Library (2020).

(Note: if you need to cite a blog, tweet, or other social media post, look at the Citing Sources guide or ask your librarian.)