The seat had two ways it can be installed in the car: 1. You can run the seatbelt through the channels in the seat itself or 2. You can install the base that comes with the seat using either the seatbelt or the LATCH connector. The base can stay installed in the car and you would simply remove the seat to take the baby from the car.
Using the infant base is very easy, and only needing to install it once instead of every time is very convenient.