You may just want to capture Pokemon but also be on the lookout for Pokestops. Travelling to Pokestops will allow you to get Pokeballs, Eggs, Potions and more.

Pokéstops are an easy way to collect items, eggs, and experience. Each one is indicated on your map, and you can click them even if you're not in range yet. You won't be able to check in until the Pokestop is close by, but it's an easy way to see where a Pokestop is located before checking in there. When a Pokéstop is within your range, you'll want to tap on it. This will bring up a screen, swipe across and you'll be rewarded with a variety of items. The items in questions can range from eggs, to various different kinds of Poké Balls, to revives or healing potions for the Pokémon in your roster. Pokéstops are important or iconic areas around the city you are in. They may be special benches with dedication plaques, or permanent art installations, or historic landmarks. They will never be something as mundane as a stop sign. They will also never be in a location that is not accessible to the public, like inside a private building, or beyond a locked gate.