Security for loans is discussed later.
Commercial lenders include banks, non-bank lenders (e.g. organisations such as RAMS or RESIMAC which are mortgage originators), building societies and credit unions. Sometimes you can access debt from these organisations via a mortgage broker who will compare the features and costs offered by several organisations.
When people are borrowing in a commercial manner, there will be a lender, a borrower, an interest rate and a repayment period.