Question

This is for personal finance but theres no one there

what type of interest is added to the principal in the account, so that the interest generates its own interest?

Answer 1

It is called compound interest - provided you leave the interest in the account.

Answer 2

The addition of interest to the principal amount in the account, deposit or loan it's called Compound interest, being the outcome of reinvesting the interest (interest on interest), in that way the interest in the forthcoming term is a gain on the principal amount with the preceding collected interest; instead of paying it out at once.

Its earning interest on the deposited money and on the interest already earned.