The other comments explains it in pretty good detail, but when I was learning my teacher explained it sort of like a mnemonic.

1 + 1 = 2 is read "one plus one equals two"

1 + 1 == 2 is read "one plus one is equal to two"

1 + 1 === 2 is read "one plus one is really equal to two"

And you hit the nail on the head, is that === is type explicit while == is implicit.