Federalism comes in many forms. At a most basic level, it can be integrative or devolutionary. Integrative federal systems come into being when several independent political communities agree to unite themselves in a larger political association. Devolutionary federal systems come into being when a single political community devolves political power to smaller groups or regions which seek a degree of independent self-Government. Actual federal systems can be roughly classified into either of these types, although on close inspection, many federal systems combine both features in some respect or another.