Extension cords are handy but can cause some problems if they are not used properly. A quality extension cord should match the project you're using it for. While cords may be exchanged for similar uses, most people quickly realize that they need more than one kind of extension cord in their homes. First, there are indoor and outdoor cords. An outdoor extension cord can withstand elements including water. They usually have a thicker diameter because they can handle a larger current. Most outdoor items, like an electric lawnmower, need more current. You can use an outdoor model inside but never an inside model, outside. Color is also an option. Many outdoor models come in either green or orange. Indoor extension cords are usually either brown or white. Extension cords come in a variety of lengths. Longer cords have a lower capacity than shorter extension cords.