What is the basis of classification of algae

Explanation-
Algae are classified into three groups on the basis of type of pigment present in them.
Chlorophyceae
Phaeophyceae
Rhodophyceae
Chlorophyceae contain chl a and chl b that impart green color to the algae.
Phaeophyceae contains chl a, chl c and a brown colour pigment fucoxanthin, due to which it appears brown in colour and is called "brown algae".
Rhodophyceae contains chl a, chl d and phycoerythrin which is responsible for its red appearance and thus called "red algae".