Multiple Narrative Modes

Usually a story will keep to a single perspective throughout. Normally this will be one of the following:

First Person: The lead characters describe their adventures as though recounting them to you personally.

I went over to the bar and ordered myself a drink.

Second Person: Told from the point of view of someone on the sidelines. Often a friend.

"You went over to the bar to order yourself a drink."

Third Person: Often known as the 'omnipresent' perspective. Events are simply described as they happen.

Bob went over to the bar and ordered himself a drink.

Occasionally, however, a story will change the type of perspective it uses, often between chapters, and will go from, for example, Third to First Person, Third to Second, and so on.

Related to Switching POV, where the story follows different characters or sets of characters.

Examples of Multiple Narrative Modes include:

Literature

The Bartimaeus Trilogy has multiple narrators, one of which is first-person and the rest of which are third-person.
Animorphs does this at one point, switching from first to third person.
Arcia Chronicles are written predominantly in third person but, starting from book two, switch to first-person whenever Gerika becomes the POV character.
The Matthew Swift books switch between "I" (when the narrator is Matthew himself) and "we" (when it's the "blue electric angels" that possess him). This switching happens extremely frequently, sometimes even within the middle of a paragraph.
The frame story of If on a winter's night a traveler uses Second Person Narration. All the internal stories are narrated in either first or third person. This is sometimes used to refer to both narrators simultaneously. For example, in the first novel read by the frame protagonist, the narrator is introduced thusly:

I am the man who comes and goes between the bar and the telephone booth. Or, rather: that man is called "I" and you know nothing else about him, just as this station is called only "station" and beyond it there exists nothing except the unanswered signal of a telephone ringing in a dark room of a distant city.

Blood and Iron by Elizabeth Bear is mostly written in the third person, but about two-thirds of the way through the book, the primary protagonist magically gives away her name, and all of her POV sections from that point on are in the first person.
Slaves of Spiegel by Daniel Pinkwater mostly switches between different first-person narratives, but occasionally it goes into third-person omnipotent when there isn't a convenient first-person narrator. The first time this happens is in a short chapter called "An Unnamed Third Person Who Knows Everything That Happens In This Story Speaks".
The first two Dexter novels are written entirely in the first-person, from Dexter's POV. Round three mixes it up when the reader gets intermittent third-person visits from Dex's stalker.
This Charming Man by Marian Keyes has four narrators, two of whom are first person and two of whom are third person limited.
In My Immortal, the beginning of fake Chapter 39 is told in first-person (the narration style of the actual story), but when B'loody Mary Smith shows up, the narration abruptly changes to third-person.
In Handle With Care by Jodi Picoult, all chapters but one are in second person perspective, using "you" to refer to Willow. The final chapter is told from Willow's first person perspective.
A Visit From the Goon Squad, by Jennifer Egan, rotates narrators and perspectives with each chapter, including one that is formatted to look like a footnote heavy article in Details magazine, and a 76-page PowerPoint presentation.
A Portrait of the Artist As A Young Man is almost entirely told in the third person, but lapses into first-person diary entries at the very end.
Some chapters of American Psycho are told in the third person, as opposed to the first-person narrative of the rest of the novel.