diff --git a/doc/how-it-works.md b/doc/how-it-works.md
index 3598d61a..d8738374 100644
--- a/doc/how-it-works.md
+++ b/doc/how-it-works.md
@@ -24,7 +24,19 @@ User reconciliation loop takes care of reconciling user provided configuration,
 
 ![reconcile](../phases.png)
 
-## Operator Status
+## Operator State
 
-Operator status is used for storing any configuration events or job statuses managed by the operator.
-It helps to maintain or recover desired state even after operator or Jenkins restarts.
\ No newline at end of file
+Operator state is kept in custom resource status section, which is used for storing any configuration events or job statuses managed by the operator.
+It helps to maintain or recover desired state even after operator or Jenkins restarts.
+
+## System Jenkins Jobs
+
+The operator or Jenkins instance can be restarted at any time and any operation should not block the reconciliation loop so we implemented
+custom jobs API for executing and verifying status of them according to operator lifecycle.
+
+Main assumptions are:
+- do not block reconciliation loop
+- fire job, requeue reconciliation loop and verify status next time
+- handle retries if case of failure
+- handle build expiration (deadline)
+- keep state in the custom resource status
\ No newline at end of file