Real estate agents have a variety of tasks that fall within their job description. Agents are responsible for selling land and property and will often charge a percentage of the sale price as their fee. They need to work out financial agreements, or mortgages, that enable the buyers to pay for their land or property over a time. The geographical area that an agent works in is their area of knowledge. The agent needs to know trends within the local property market as well as realistic prices for the various property and land they have to buy or sell. Negotiation is a key part of the agent's work life as they act as the intermediary between buyer and seller and will often negotiate on their client's behalf.