Accepting credit cards requires a payment processor like Square or Stripe, a merchant account, and hardware like POS terminals. Fees range from 1.5% to 4%.

Dallas-based processor TransFirst today began marketing a Web-based payments-processing engine that was developed by a company it acquired a year ago and is currently being used by 3,500 merchants.

A payment gateway encrypts and transmits customer data; a processor moves funds between accounts. Both are essential for online credit card transactions.