Algae [derived from seaweed “alga” (Latin) and “phykos” (Greek)] are photosynthetic organisms possessing chlorophylls and simple reproductive structures but lacking true root, stems and leaves. They occur in different habitats including extreme ones. Apart from seaweeds, most algae are extremely small culminating in millions of cells in a small volume of water. Ten divisions of algae namely Bacillariophyta (diatoms), Cyanophyta or Cyanobacteria (blue-green algae), Chlorophyta (green algae), Euglenophyta (euglenoids), Chrysophyta (golden-brown algae), Phaeophyta (brown algae), Rhodophyta (red algae), Pyrrhophyta (fire algae, dinoflagellates), Xanthophyta (yellow-green algae) and Cryptophyta (cryptomonads) are commonly recognized.

Algae exhibit different kinds of movements that mimic a dance. Such movements include sliding, gliding, rotation, spinning, gyrating, summersaulting, oscillating, wriggling and flexing of body. Algae, when alive, float on water especially in the euphotic or lit zone, and sink to the bottom of a water body when they die or thrown out of the euphotic zone as a result of turbulence.

The lecture gives a vivid account of the importance of algae, stressing the market or commercial values of products from algae which are multimillion dollar industries in the world. They help in the purification of the aquatic environment via processes such as bioremediation (pollution control), carbondioxide sequestration or removal and wastewater treatment. In addition they have been employed in land reclamation, reforestation, food security, renewable energy,  biofuel, medicines, pharmaceutical industries, bioproducts (bioplastics), food, food supplements, fodder, aquaculture feed. They have also been used as biochemicals, global warming antidote, industrial products-phycocolloids (alginates, agar, carrageenan, minerals etc), agriculture (biofertilizer), nanotechnology, environmental studies, cosmetics, nutraceuticals etc.; hence algae can be referred as the HOPE of the PRESENT and FUTURE.