A carbocation is a positively charged ion that contains a carbon atom with only three bonds instead of the usual four. This results in an electron deficiency, making carbocations highly reactive. They often form during chemical reactions, such as in the process of alkyl halide elimination or nucleophilic substitution. Carbocations can be classified based on the number of carbon atoms attached to the positively charged carbon. They can be primary, secondary, or tertiary, with tertiary carbocations being the most stable due to greater electron-donating effects from surrounding carbon atoms. Understanding carbocations is essential in organic chemistry for predicting reaction mechanisms.