A carbocation is a molecule in which a carbon atom has a positive charge and three bonds. We can basically say that they are carbon cations. Formerly, it was known as carbonium ion. Carbocation today is defined as any even-electron cation that possesses a significant positive charge on the carbon atom.

The different carbocations are named on the basis of the number of carbon groups bonded to the carbon. The carbocation can be termed as methyl, primary, secondary or tertiary on the basis of how many carbon atoms are attached to it:

i) Methyl carbocation: If no carbon is attached to the carbon with the positive charge it is simply called as methyl carbocation.

ii) If one, two or three carbon is attached to the carbon with the positive charge it is called the primary carbocation, secondary carbocation, tertiary carbocation respectively.