The mind meld is an action that is best known from Star Trek. In Star Trek, Vulcans have the ability to link their minds with the mind of another person and through that tap the other mind for memories. This is usually done by the Vulcan placing his or her fingertips on the other person's "meld points" (located on the face for humanoids), and then reaching out mentally. This enables the Vulcan to share the other person's memories and emotions. While the subject of the first mind meld in Star Trek is human, the technique is not limited to humanoids: judging by later episodes, any sentient being can meld with a Vulcan.
The Vulcan mind meld first appears in Season One of Star Trek: TOS (Episode 9: "Dagger of the Mind"), where it is used by Spock to determine whether the information he and Doctor McCoy are being given is "real or delusion." According to TOS, Vulcans do not usually meld with non-Vulcans, as melding is a personal part of their private lives. "Dagger of the Mind" marks the first time Spock has melded with a human, although it is far from the last.