If every day is a holiday, is any day really that special? The answer, especially if you’re on social media, seems to be a resounding yes.

The sheer number of “holidays” people celebrate — and by celebrate, that mostly means tweet — is staggering. (There are only 10 federal holidays in the United States, after all.)

On Friday, for example, #NationalCameraDay was a trending term on Twitter. Saturday was National Meteor Watch Day, and on Tuesday, you could celebrate Compliment Your Mirror Day by practicing self-acceptance and telling yourself you are beautiful and strong.

But where do these offbeat holidays come from? And are they legitimate?

While organizations and companies invent a lot of them, the majority come from people and, yes, many are better vetted than you might think.