The first thing that pops to mind is, 'The character whose eyes we are seeing the story through.'
Yet point of view isn't just who experiences something, it is the way in which they perceive the things around them.
Have you ever read a piece of fiction where the author wrote from multiple viewpoints, all of which sounded more or less the same? It's easy to say that the problem is the inability to distinguish one character's "voice" from another but I believe that point of view is a big part of the solution to that problem.
You might be familiar with this question:
'Is the glass half full or half empty?'
The answer lies with the individual and their own perception. However, it is important to remember that, while the question prompts for one of two answers, there are countless ways to approach it.
'It depends on whether it was just poured or tipped.'
'Half of it is full of water, the other half is full of air.'
'It's empty. They just drew a line across the center of the cup.'
'No half about it. Looks like a jello shot.'
'Eggs came before chickens - dinosaurs had them!'
Point of view is the way your character perceives the world but also how they approach it. Even answering an over-hashed psychology question from different angles can bring about a hint of insight into a personality.
It is important to think about your characters' actions and opinions. Remember that a fictional character is not a reflection of yourself and your morals. They need to have an agenda of their own. Only then will they come to life.
How do you tackle point of view in your writing?