Many tents offer footprints as an aftermarket add-on. A footprint is a piece of fabric that matches the shape of the tent floor. It often will clip into your tent poles or stake system to integrate with your setup under your tent.
The footprint offers protection against sharp objects on the ground and may increase the lifespan of your tent. However, carrying a footprint adds to the weight of your pack. So, you need to balance the need to protect your tent with the added weight of the footprint.
For ultralight tents such as the Hyperlite UltaMid or Zpacks Duplex, a footprint is often important to preventing damage. That’s somewhat ironic, as the tent is meant to be as light as possible.
For that reason, sometimes a slightly heavier floor build, as on the REI Arete, makes more sense, as you can leave the footprint behind. For car camping, a footprint is always a good idea, as it will increase the life of your tent.