What is photoperiodism. How are plants classified based on photoperiodism?

Explanation

i. Long day plants: The plants that require long critical day length for flowering are called long day plants or short night plants. Example: Pea, Barley and Oats.
ii. Short long day plants: These are long day plants but should be exposed to short day lengths during early period of growth for flowering. Example: Wheat and Rye.
iii. Short day plants: The plants that require a short critical day length for flowering are called short day plants or long night plants. Example: Tobacco, Cocklebur, Soybean, Rice and Chrysanthemum.
iv. Long short day plants: These are actually short-day plants but they have to be exposed to long days during their early periods of growth for flowering. Example: Some species of Bryophyllum and Night jasmine.
v. Intermediate day plants: These require a photoperiod between long day and short day for flowering. Example: Sugarcane and Coleus.
vi. Day neutral plants: There are a number of plants which can flower in all possible photoperiods. They are also called photo neutrals or indeterminate plants. Example: Potato, Rhododendron, Tomato and Cotton