A very common term in the credit and lending world, a credit inquiry is a listing on your credit file of who accessed your credit report and on what date. There are two different categories of inquiries: soft and hard.
A soft inquiry does NOT have any sort of negative impact on your credit scores. In fact, you are the only person who sees soft inquiries when you ask for a copy of your own credit report. You may receive a soft inquiry when a bank pre-qualifies you for a mailed credit card offer.
A hard inquiry can lower your credit scores and will be visible to anyone who checks your credit report. You will probably receive a hard inquiry when you apply for a car loan or a credit card. These examples constitute your official effort to get credit. Each time you apply for credit, the resulting inquiry will remain on your credit report for two years.