What is the Recovery system in preparing the testcases?

Recovery testing is nothing but to check how well the application manage to come back from abnormal conditions to normal condition.
Example: If any network failure or crash happens, refreshing the page either comes back to normal or still behaves abnormally.
Test cases will be written accordingly.

Recovery System is nothing but getting the system from the unsecured or getting any thing in wrong to correct way i.e getting from the recovery