A measure of the rate of return on a deposit or investment that provides a like-with-like comparison between alternatives. If there is €110 in an account a year after €100 was lodged in it the return in *Annual Equivalent Rate (AER) terms has been 10%. That's assuming that interest has been credited in full and that no withdrawals or lodgements were made to the account.
Savings interest rate is variable.
Interest payable is subject to Deposit Interest Retention Tax (DIRT).