The first thing the merchant account provider will ask is what kind of business are you doing. They are usually broken down in to three major categories. ecommerce and internet, retail, mail order telephone (moto). Depending on what type of business your doing and how your doing it will affect the prices you receive.
eCommerce and Internet
When doing e-Commerce type transactions you'll need a Virtual Terminal and a Payment Gateway. These should be included in your merchant account. The Virtual Terminal is like a credit card machine but for the web. The payment gateway allows you to perform transactions on your website.
Mail Order and Phone
These types of transactions can be either done on a Virtual Terminal or physical terminal.
Quick Books Transactions
Quick books is a popular accounting software among small businesses. The software covers most types of businesses and allows you to perform transactions from within it.