Agency And Agreement Fees....

When you want to rent a house in Nigeria,the first thing you hear is 'Agency and Agreement'' Fees...What is the meaning of this?I thought what you pay when renting is caution fees to safeguard anything you damage whilst in the house? Even the Owner of the house collects agency and agreement fees almost as high as the rent itself... What kind of practise is this and why are people via IFTTT