What Does An Agency Agreement Get You?
Regardless of which side of a real estate transaction you are on, its important to have an agent representing you in some way. Why? You get LOADS:
L Loyalty We represent you, and only you.
O Obedience You ask. Well find out.
A Accountability We protect your money, your information, and your interests.
D Disclosure/Due Diligence Well tell you everything we know and try to find out more.
S Skill We want you to get the house you want, for the best price, with the least hassle.
So, once you find a Realtor with whom you are comfortable, you sign an Agency Agreement, agreeing to hire your Realtors firm (and a particular agent) as your personal representative who, by law, must represent your best interests to the best of his/her ability for a specified period of time. That firm and agent then represents you, the Buyer/Seller, in any real estate transaction during that agreed time period, unless you authorize otherwise.
While it seems pretty obvious that the Agent either represents only the Seller or only the Buyer in a real estate transaction, in the state of North Carolina there is the option of the Agent representing both the Buyer and the Seller at the same time. To best explain these nuances and avoid confusion, please carefully read the Working with Real Estate Agents brochure mentioned in the Understanding Agency link. If you want an example of how Agency works, below is a very basic visual "explanation" of the different types of agency using a sports analogy.

Actual Forms:
Buyers & Sellers: read the Working with Real Estate Agents Brochure
Buyers: read the Exclusive Right to Represent Buyer: Buyer Agency Agreement Sample Form
Sellers: read the Exclusive Right to Sell Listing Agreement Sample Form
Buyers & Sellers: read the Professional Services Disclosure & Election Sample Forms