The average age is 65.
There are two main types of dentures: complete and partial.
Complete - when all of the teeth are missing
Partial - when some natural teeth remain.
When a prosthesis is created it is made to fit snugly over your gums and replace missing teeth. They can be removed and put back in the mouth as needed.
Like a new pair of shoes, It may take some time to get used to something new in your mouth.