A real estate agent is more than just a "sales person." They act on your behalf as your agent, providing you with advice and guidance and doing a job - helping you buy or sell a home. Due to the fast changing market, the data on available listings is not 100% accurate. There are times when you need the most current information about what has sold or is for sale, and the only way to get that is with an agent.
There are two types of agents, "Buyer's Agents" and "Seller's Agents". It used to be common for all parties involved to work for the seller, hence the term "Seller's Agent". Nowadays, you will most often find a different type of agent, the "Buyer's Agent". If you are in the market to buy, it would be advisable to use a Buyer's Agent. They can make recommendations on what terms and prices to offer as well as negotiating a deal with your best interest in mind. If you happen to be working with a Seller's Agent, never disclose to them the top dollar you are willing to pay for any property. Keep it narrowed down only to things that you would tell the seller directly.