Some stories are told from a single perspective, in a single location, over a short span of time (for example, Emperor’s Soul by Brandon Sanderson), but in general, the longer a story is, the more complex it becomes. Most novels feature between 2 and 6 different point of view characters, each with their own cast of supporting characters. They engage multiple narrative threads, spanning a wide range of locations and moments in time.
Most character perspectives are revealed as part of the overall process of revealing character, see 103 on engaging and revealing characters, but POV characters have the added challenge of conveying the details of the story while also remaining true to their own perspective.
In addition to choosing a POV character, there is also the question of which voice to use; first, second, third limited, or third omniscient, and whether the story will be told in past or present tense. At the moment past first and third limited are most common within fiction.
Every character in a story has a perspective, a unique way of perceiving and interpreting the world around them, revealed to the audience through what a character says and does. Every story also relies on one or more characters to convey the story to the audience through their perspective. These are known as POV or point of view characters.