Status effects have been around since the first generation of Pokémon games (RBY) and have since grown in number and been greatly expanded on with introduction of new moves, abilities and items.
Status effects can now occur not only by using a move that will directly inflict that condition but also through secondary effects of moves, abilities and, with the fourth generation's introduction of Fling, thrown items.
There are a variety of status effects. Each has unique qualities that make them useful in their own right. Use the list above or below to navigate to the page detailing all information pertinent to the status effect you are looking for.