When you start writing a book, one of the first questions you have to ask yourself is what point of view are you going to focus on? There are several different paths you can take and explanations about why you might want to choose one over the other.
1st Person POV: These are the "I" stories, books that are generally only in a single person's POV. The narrator is the main character. You see this quite often in YA books like Hunger Games, Divergent, and The Lightning Thief. In some cases, a 1st person POV might have multiple character views. One of the Mercy Thompson books, while primarily told from Mercy's view, switches to her mate, Adam's view partway through the book. This is effective so long as you indicate that you're switching the POV. Generally though, you want to just stick with one character. KA Applegate wrote a series called Animorphs in which each book had a single POV, but it switched characters from book to book. In one book you read about Rachel. The next focused on Tobias. Still, each individual book was through the eyes of one person.
2nd Person POV: These are the "you" stories, ones that make the reader the main character, essentially. This is an excellent POV to use when you're writing a choose-your-own-adventure book or blog posting. I've also seen this work well in poetry. Some examples of 2nd POV books include The Night Circus, Bright Lights, Big City, and All the Truth That's In Me. Arguably, second person point of view is one of the hardest POVs to write. If you don't do it the correct way, readers can become confused or lost in your writing. In some cases, they might feel offended, feeling that the writer is saying something wrong or rude about them. You have to remember that this is just another form of writing.
3rd Person POV: There are a couple versions of 3rd person point of view that we'll go into. In general, these are the "he/she" stories, so it's the author telling a story through other characters. Third person POV is likely the easiest way to tell stories from multiple POVs. Some good examples, in general, include The Giver, Ender's Game, and The Game of Thrones series.
3rd Person Omniscient: In these stories, the narrator knows all the thoughts and feelings of each character and doesn't focus on just one. Everyone, more or less, gets page time and there aren't many secrets that the reader doesn't know. Some examples include Redwall by Brian Jacques.
3rd Person Limited: Limited means that the narrator only relays the thoughts and feelings of particular characters. In essence, the narrator zooms in on a character and gives a closer look into that person's thoughts and habits. No longer does the read know what everyone is thinking. Some good examples include Harry Potter and Alpha Omega.
The next questions to ask are, why choose these different POVs? What works best for my book? Should I just have one POV or many?
That really depends on what you're writing. If you have an epic fantasy with different races and locations where battles occur, you may consider writing 3rd person so you can explore more of your realm. Think of Lord of the Rings. Initially, we follow everyone on the journey, but eventually, the characters split off with Aragorn, Legolas, and Gimli headed in one direction, the hobbits going in another, and Gandalf going a third. You get to see what's happening to everyone through the story without having to hear it from another character.
If your book is focused on a single character and you want to make sure the readers can get into her head, then you may consider first person instead. Hunger Games and Divergent both let you see the world through the eyes and minds of the primary character. Could it have been told through multiple POVs? Possibly, but it may not have been as effective.
Sometimes you may write a book with multiple characters in mind, only to realize later that it's better to have one focus. Or, in the case of a dear writer friend of mine, in order to enhance her romance book, she had to include a brand new POV. She admitted it made the book that much stronger.
Experiment. Play around and write a couple chapters and see what works better for you. You may not realize your book is missing a POV until you finish it or a beta reader suggests that they wanted more information from another character. If that's the case, don't be afraid to rewrite part of the story. I had too many POVs in one of my books and I dropped out everyone but the main character and that made the book more focused and much stronger.
Good luck, and happy writing.