If I don't recognize the charge, I inquire by visiting my online banking first and looking at the Description of who charged me (the name of the company). There should also be a phone number in the description so you can call them to find out that the charge was for if you don't recognize it.
In reviewing my recent credit card activity I saw a $39.95 charge from GFSSUPPORT.COM with the phone number 888-266-4759 that I did not recognize. Before calling the number I did some online research using Google and other search engines. Mainly I use the reverse phone lookup on searchbug.com since they provide free access to white and yellow pages so if it's a legitimate business that has been around a while and their phone number is in the business directory it should show up for free. It's a good test to see if a company has been around long enough to have their phone number listed.
In the above case, that phone number was not found at the time of this posting in searchbug.com. The phone number is all over Google. I called GFSSupport and used their chat service and found out that I had been charged by a company called lifestyledealsnow.com (a supposed company that sells health related information and supplements). The only place I purchase health supplements is from my local health food store or vitamin shop so now I was very suspicious.
I asked them for the origination sales order and the IP address of the computer that placed the order. They could not provide that information and gave a complete run around. They also pointed me to another web site called chargehelper.com which is nothing but a web site that threatens you if you issue a chargeback stating that you will be ban from using your credit card online. This is utter nonsense and the only reason they would have a web page that shows this information is if they get threatened about chargebacks constantly.
These guys should be reported to every attorney generals office in every state for their business practices. GFS Support handles credit card charges for multiple web sites, most of which are in the adult web site business. If you Google GFS Support or their toll free number there are very few valid links with information are returned. If you check out statscrop.com you'll see that the domain is only 4 months old and was registered with godaddy for only 1 year. Most legitimate companies don't register a domain for only 1 year.