Vector and list problem

in the last timestamp, sir has changed the list to a vector of books i.e from list to vector. In vector, we use data types other than the variable according to me so please solve my this query that how sir can change from list to vector.

@Ritesh_jindal both list and vector are template classes so you can use whatever datatype you want in them.

but book is not a datatype

@Ritesh_jindal it is a user-defined datatype, but it is a datatype nonetheless.