At some coffee shops, you will notice that baristas use tampers. Tampers are used to pack espresso grounds into the portafilter before extraction by an espresso machine. The idea is when you pack the grounds evenly every time, you can produce a quality espresso shot. This makes it harder for the water to go through the coffee grounds, allowing for a more even extraction. Tampers are easy to use, and when used the right way, helps produce amazing shots. There are four types of tampers: Handle, puck, dual-head, and weight-calibrated.
The handle tampers are the most common style of tamper. Think of an ink stamp that you have used before. Nice wooden, rubber, or metal handle with a flat base allowing you to apply more pressure when tamping. This one is great for home use. The puck tamper looks like, you guessed it, a hockey puck, and somewhat similar to an espresso distribution tool. This tamper is flat on the top, and you can apply pressure with the palm of your hand or twist and apply pressure downward. The dual-head or double-sided tamper looks similar to the handle tamper, yet has a smaller and larger flat base. This is nice if you have portafilters that are of different sizes. The fancies of the tampers are the weight-calibrated tampers. These tampers are specifically made to apply a consistent amount of pressure to ensure every time. Some espresso machines and grinders come with tampers, and they are useful if you are making your casual coffee cup at home. Expect to pay above $35 for a high-level tamper, yet note that one may not be necessary in the beginning. I suggest a handle tamper to start.