Dissociation of bases
Bases have the same net result as alkalis: They reduce the concentration of H+ ions in solution although they do not dissociate into OH- ions.
The stronger the base, the more free H+ ions it can accept from a solution.
A common base is ammonia (NH3). As it binds to free H+ ions in solution it becomes ammonium (NH4+).
The formation of NH4+ from NH3 is reversible. This means that under different circumstances the H+ might be released from the NH4+.
NH3 is therefore a base because it accepts H+ ions; but NH4+ is an acid because it donates H+ ions.
Any molecules (not just bases) that can accept and donate H+ ions are called buffers.