Hard vs. Soft Credit Inquiry
A hard inquiry happens when a lender checks your credit for a new application and can temporarily ding your score by a few points; a soft inquiry — checking your own score or a pre-qualification — doesn't affect it at all. Only hard inquiries are visible to lenders.
Multiple hard pulls for the same purpose (rate-shopping a mortgage or auto loan) within a short window usually count as one. Spacing out new-credit applications and using pre-qualification tools protects your score while you shop.