A logical clock is a mechanism for capturing chronological and causal relationships in a distributed system. As physical clocks cannot be perfectly synchronized, event timestamps derived from readings of physical clocks cannot in general be used to find out the order in which events happened.

Logical clock algorithms of note are:

• Lamport logical clocks, which is a monotonically increasing software counters
• Vector clocks, that allow for total ordering of events in a distributed system.
• Matrix clocks, an extension of vector clocks that also contains information about other processes' views of the system.

Distributed systems

Logische Uhr