A fee simple estate is the most common type. It allows the owner of the estate to keep the land forever or to devise it to someone else to keep forever. A fee simple will not end naturally.
The words "and his heirs" in a conveyance are the words of limitation that create a fee simple.
While a fee simple allows the grantee's heirs to inherit the estate, no legally recognizable interest is granted to them.
Fee simple absolute means that no limitations at all. Fee simple is the only type of estate capable of being absolute, as all other types have inherent limitations.