Whenever you authorize a creditor, employer, or other business to check your credit report, an inquiry is added to the report itself -- a note that someone has checked your credit. An inquiry usually stays on your credit report for two years.

Checking your own credit report, however, does not lodge an inquiry.

A lender considering you for a loan will look at the number of inquiries recorded there and when they took place. A large number of inquiries occurring in a short period of time may be interpreted as a sign that you are either applying for lots of credit because of financial difficulty or overextending yourself by taking on more debt than you can actually pay back.

If you're shopping around for mortgages, for example, don't let every lender you consider run a credit check. You might have to settle for slightly more approximate estimates on what the lenders can offer you, since they can't verify your credit history. But that's still better than doing all that shopping around only to find that the lender of your choice now perceives you as a less solid credit risk and wants to charge a higher rate.