Carbocation stability is primarily determined by inductive effect and hyperconjugation. Alkyl groups are electron-donating, which stabilizes the positive charge on carbon. More alkyl groups mean more electron donation and greater stability. Hyperconjugation, the delocalization of electrons from adjacent sigma bonds into the empty p-orbital of the carbocation, further enhances stability. The number of alpha-hydrogens (hydrogens on carbons adjacent to the carbocation) directly correlates with the extent of hyperconjugation.