DIN 41618 connectors are a type of connector named for the Deutsches Institut für Normung, by whom they were first standardised.
This particular type of DIN connector is mainly used in broadcast audio installations, for example in terminating multipair audio cables. This is useful in applications such as wiring between different studios.
DIN connectors were first used in audio equipment, which is also what they are most commonly associated with nowadays. The different numbers accompanying the connector type dictate what specifically they can be used for, as each DIN connector has a different configuration of pins, making them very versatile. For example, DIN 41617 connectors can be completely different from DIN 41618.
DIN 41618 connectors can have different numbers of rows and pins. They can also have differing levels of resistance and varying current ratings. Their different maximum and minimum operating temperatures determine what environments that they can be used in.