>[!abstract]
>The mean sojourn time (or sometimes mean waiting time) for an object in a dynamical system is the amount of time an object is expected to spend in a system before leaving the system permanently. This concept is widely used in various fields, including physics, chemistry, and stochastic processes, to study the behavior of systems over time (Wikipedia, 2025).
>[!related]
>- **North** (upstream): [[Markov processes]]
>- **West** (similar): [[Mean first passage time]]
>- **East** (different): [[Instantaneous transition]] (zero sojourn time)
>- **South** (downstream): [[Residence time distribution]]