An "inquiry" is a listing of the name of a credit grantor or authorized user who has accessed your credit file. Credit grantors post an inquiry before offering you a preapproved credit application.

Some examples of those who can access your credit files are:
Credit Grantors
Collection Agencies
Insurance Companies
Employers

While inquiries on your credit report can reduce your credit score, they only account for 10% of your total credit score. Payment history and outstanding credit balances impact your credit score the most.

This allows a few different mortgage companies to pull credit within that 15 day window and not affect your score as it would normally when you are in the process of obtaining a mortgage.

Not all inquiries effect your credit score. Such as inquiries made by creditors you currently have an account with.

Also, inquiries made by you will not impact your credit score.

Many times you will have to write an explanation letter when applying for a mortgage if there are a large number of recent inquiries. The lender wants to make sure you have not taken on new debt that has yet to show up on your credit report.

Allow it is true that too many inquiries can have a detrimental effect on your credit score, the scoring system allows for unlimited inquires in any 15 day period to only count as one inquiry.

The scoring system works that way to allow consumers to "shop" for credit without fear that their scores will be damamged.

You will damage your credit if you spread your mortgage shopping over many months. Because the market can change from day to day, it makes little sense to do this in any case.
Try to keep it within a two week time frame.

Inquiries not initiated by you do not negatively affect your credit score. When credit card companies pull your credit report to offer you credit without you first applying for it, your score is not affected, regardless how many companies pull it or how often.

Inquiries made by junk mailers and such does not affect your score since these are not consumer initiated applications. However, if you respond to one of these offers, then a credit file inquiry is made and your score is lowered. What should also be noted is that if your credit file is perfectly clean, you should not even be concerned about this 5 point penalty on credit inquiries .

Your credit report only shows inquiries made in the past 90 days. After the 90 day period inqueries are removed from your report.

Opening a new credit account doesn�t harm your credit score dramatically especially after you make the first payment. However, credit inquiries can negatively impact your score. Generating many credit inquiries is a flag that you are trying to secure a large amount of credit or you are being turned down by lenders and have to apply elsewhere.

If you need a loan, do your rate shopping within a focused period of time, such as 30 days. FICO scores distinguish between a search for a single loan and a search for many new credit lines, in part by the length of time over which inquiries occur.