Inquiry is the term used by the credit and debt industry to describe what happens when businesses request copies of your personal credit history. Certain inquiries can hurt or lower your credit score while others are harmless!
Businesses, with permissible purposes can request a copy of your personal credit history and when they do, these inquiries appear on your credit reports and usually remain there for 1 to 2 years.
On the other hand, certain inquiries are either illegal, unethical or both. These come from debt collectors who are trying to "get your attention" by pulling your credit report.
It works like this. They know most consumers check their credit reports on a regular basis, so they conduct an inquiry (or in many cases actually add negative information by reporting a delinquent or expired account as "active but overdue"). When consumers check their credit report and discover the negative information, they often contact the collection agency to get it removed, which is exactly what the collector, who put the information there, was hoping for.