It's a terrible name. The math answer is what I would give.

No. ArrayList is thread safe and implements the collections API. Vector doesn't. Though if you're using Java, there's almost no instance where you would want to use a Vector instead of ArrayList.

This is such an understated but useful description in this context. It's also how I understood algebra for applied matrix computation.

It's a dynamically-sized list of objects of the same type stored contiguously in memory.

dynamically-sized: The size of it can change as needed.

list: It stores multiple things together.

object: A bit of programmer defined data.

of the same type: all the objects in the list are defined the same way

stored contigiously in memory: if you think of memory as a bookshelf then all the objects on the list would be stored right next to each other on the bookshelf rather than spread across the bookshelf.

Many things like each other lined up in a row, and you can take some away or put more in.

It's like a fancy list.