I am a little confused as to how many different car seats a newborn / baby / toddler will need?

I have registered for a Chicco Keyfit 30 Magic Infant Car Seat & I know there will come a point my infant will outgrow that car seat and need a new one and then I imagine from there they will outgrow it and need a booster?

is there a time frame that babies outgrow their infant seats and how many more will we have to buy!?