I've seen it described as the social media site for people who hate social media.

The story goes that when Facebook was becoming mainstream, a guy came along and decided he hated Facebook. So he hired a software engineer at his company to help him make a site that wasn't Facebook in any way. Basically, the criteria for the site were that he could post photos on it and follow people whose photos he wanted to see, and he didn't have to see anything he didn't care about.

So Tumblr is a very self-curated social media experience where there's no brands or celebrities. You just search for stuff by hashtags, follow blogs that interest you, and post and reblog stuff at your whim. Everything is displayed on your dashboard chronologically, and the only stuff you'll find on there is stuff from people you follow.

The closest thing I'd describe it to is Twitter, but it's more blogging than microblogging and the more direct interaction between you and the people you follow can feel a lot more personal than other forms of social media. You can send people messages that can be answered in a public post in addition to the usual direct message system. There's no character limit on posts or anything, and people will write full short stories and stuff. It also has more of a sense of permanence, in my opinion. It isn't uncommon to see popular posts crop back up that were created in 2012-2014.