Why does interest in money exist?

Question

What is it for and why? I found a lot of questions on interest rate but not what interest itself is

Thanks in advance 🙂

Edit: Thank you for all the replies i am now a financial god of wisdom, i’m not going to reply to unless something is unclear to me but comments will all be read

In: 9

Answer 1

Because if i lend you 100$ and expect you to pay me back in a week, i have 100$ less until you repay me.

So i need a reason to give you 100$. If you’re not a friend, that reason can be getting 110$ back. That’s interest.