View mode is a minor mode that lets you scan a buffer by sequential screenfuls. It provides commands for scrolling through the buffer conveniently but not for changing it. Apart from the usual Emacs cursor motion commands, you can type
SPC to scroll forward one windowful,
DEL to scroll backward, and
s to start an incremental search.
View-quit) disables View mode, and switches back to the buffer and position before View mode was enabled. Typing
View-exit) disables View mode, keeping the current buffer and position.
M-x view-buffer prompts for an existing Emacs buffer, switches to it, and enables View mode.
M-x view-file prompts for a file and visits it with View mode enabled.