What heck does POV stand for? It stands for Point of view and is normally referred to as the story-teller's voice. There are many (POV) story-teller voices out there, but the one most commonly used is the first person narrative form, distinguished by the pronoun “I”, as in I am, I did, I was. The first person narrator is popular possibly because it's the narrator first used by most of us, and, because of its familiarity, many never see a reason to venture beyond it.
However, some authors after they have written in first person for a while might feel the urge to gravitate toward the omniscient narrative form, for one reason or another. This—the all-seeing, all-knowing narrator—gives an author more flexibility as it allows stories to be told from multiple viewpoints. The omniscient, or voice of God narrator, is very easily identified as the author's voice, so one's readers might ask questions. For example, is the author an expert on all things mentioned in his or her novel? The omniscient viewpoint was fine in Dickens' day; however, does the average modern author have the authority to state that it was the best of times and it was the worst of times?
If one feels the first person and omniscient voices are problematic, what's left? Actually, the most popular, modern point of view form is the third person, past tense, limited omniscient narrator. In this voice, as with the omniscient, you can narrate from multiple viewpoints. In this voice, your character actually becomes the story-teller rather than its author.
Third person, limited omniscient comes in many varieties. The story can be seen from a distance, if you wish, or your reader can be closely immersed in the story from inside your character's mind, both tactilely and emotionally. In close immersion, your reader sees, hears, tastes, smells and feels exactly what your character senses. With close immersion, your reader might actually become your character for a while, allowing him or her to escape the confines of a reality and be transported to exotic, dangerous or romantic places to have the adventures only imagined in real life.
A word of caution: when using the limited omniscient POV, you can only write about what your POV character senses. He or she is limited, as in real life, to knowing, seeing, hearing, tasting, smelling and feeling only that which her senses allow her to know, unless, of course, your character is superhuman or an alien life form.
Can a writer mix different points of view? It can be a challenge, but there are writers who can make this work. Sometimes writers might switch from first to third person; however, there is a risk to this in that readers may or may not appreciate the use of this literary element in this way. Another trick some authors use is to begin a story using the omniscient viewpoint, then zoom inward via the third person, limited omniscient form much like a motion picture camera's telephoto len, into their main character's mind as he or she copes with his or her world.
Which POV should you use? It really should depend on the best way to show the story, but usually writers start out using the POV that feels most comfortable. Only though experimentation can a writer find the form that best suits his or her individual and creative needs or personality. So please do experiment; play around with narration until you find your own special voice. Your readers thank you for it.