This service is for single party domestic checks payable to the owner(s) of the account. An example would be a check written to you for a wedding, birthday or graduation gift or check(s) you collected because you sold some goods (example school fundraiser or similar). But it's not just limited to personal checks, mobile deposit works for stimulus payments and payroll checks, too.
You may not use this service to deposit foreign checks drawn on a foreign bank; money orders; or checks payable to an individual not on the account.