An experience was the practical contact and participation in an event by an individual. The record of this event became part of their memory. Some, such as Benjamin Sisko, believed that an individual was the sum of their experiences. Past experiences could be used as a guide for an individual; however, there were limitations for there might be experiences for which an individual was never prepared for. (TOS: "The Cage"; DS9: "Emissary")
The Talosians of Talos IV were capable of reaching into the minds of their specimens and creating an illusion out of an individual's experience for them to relive. For example, Captain Christopher Pike's experience of his mission to Rigel VII. (TOS: "The Cage", "The Menagerie, Part II")
In 2268, Spock postulated that whatever overwhelmed the Starnes Exploration Party must have done so with incredible speed otherwise Professor Starnes would have provided details of his experience. (TOS: "And the Children Shall Lead")