When someone reviews your credit, it will be a hard inquiry or a soft inquiry.
Soft credit inquiries
Soft inquiries do not affect your credit and only you can see soft inquiries on your credit report.
Hard credit inquiries
Hard inquiries are viewable by anyone accessing your credit report and they affect your credit.
When a hard credit check is performed, your total number of hard inquiries is added to your credit report. The number of hard inquiries and length of time between them will determine how many points your score will decrease after a hard credit check is performed.
Aside from affecting your credit score, the number and frequency of hard inquiries are often used by lenders to determine if they will extend credit to you.