This is a common question asked by individuals applying for instant credit cards. After researching the three credit bureaus (Experian, Transunion, and Equifax), SmartCreditChoices.com found this explanation from Transunion’s website to be the clearest answer to the question, “How do inquiries impact a credit score?"

An inquiry is recorded on your credit report every time you, one of your creditors, or a potential creditor obtains a copy of your credit report. A common misperception is that every inquiry decreases your credit score a certain number of points. This is not true. Typically, the presence of inquiries on your credit report has only a small impact on your credit score, while certain types of inquires have absolutely no impact on your credit score. Inquiries have less importance than delinquencies, balances owed, and the length of time you have used credit. Inquiries are usually more important on your credit score if you have a limited credit history.”

Source , http://www.transunion.com