Over the weekend, a tweet by a correspondent for The Independent got people sharing some of the things they learned in life long after everyone else around them probably knew them.
We're not talking sordid secrets here either - just plain obvious truths that have eluded some regular people.
On Sunday, Jon Stone asked the question: "What are some really obvious things you didn't realise until embarrassingly late in your life?"
Stone's tweet received more than 1,800 replies proving that obvious facts can sometimes go unnoticed or misunderstood for years.