The Korean alphabet has 24 basic characters. These are the basic "building block" characters of the Korean alphabet. All other characters are made up of combining these 24 characters.
The reason there are 26 characters on a Korean keyboard is because of the compound characters ㅔ and ㅐ. These are very commonly used compound characters, so they are given their own spots on Korean Keyboards. That is why, if you use a keyboard, you may accidently count 26 characters in the Korean alphabet.
