What are trigger-start services in Windows?

In Windows, special Service Applications (or just Services) run in the background without user interaction. The are some special startup modes for these services which I want to talk about today.

Firstly, a "Trigger-start" service means a Windows service is configured to start or stop in response to operating system events (triggers) instead of always starting at operating system boot time.

Now, where would you want to use such trigger-start services? Common trigger examples include device arrival (USB or similar plug-in device interface), network availability, group policy application, or other system events. Triggers let services stay stopped until something relevant happens, saving resources.

You can check a service's triggers from an elevated command prompt:

sc qtriggerinfo ServiceName

You can set or modify triggers with "sc triggerinfo" like this:

sc triggerinfo ServiceName start/param1/param2

If you are building your own Windows services and thinking if a trigger-start option would be a good choice, consider the limitations. Trigger requests are not guaranteed to fire, such as when memory is very low. Thus, critical services may still need a normal startup type depending on your reliability needs.