A traditional "e-commerce" transaction consists of a bank account (your business account), a "Merchant" account which actually authorizes and processes the transaction, a payment "Gateway" and some form of online transaction which submits to the gateway. Click here to see a diagram.
You can think of Chargent as an online cash register or card swipe terminal for Salesforce - we take payment information (credit card or checking account number, billing information) and submit that to your merchant account via an online processor (refered to as a "Gateway", see below). In the diagram above, we handle Step 1 only. With Chargent, we send the information from Salesforce to one of our integrated gateway services such as Authorize.net. If you already have an account with one of our gateway partners, you can be up and running within 5 minutes!