This has to be the most-frequently asked question I receive from newbie clients. I can't blame them, really. It's a confusing online world out there and a lot of people who are trying to tell them how it works are really just trying to sell them their own solution. It's kinda hard to trust the validity of what they say when profit is a huge motivating force behind their persuasive suggestions.
Money is to be made at many steps along the ecommerce path.
This really is your first step toward ecommerce, unless you have chosen to go through a payment facility and are willing to give up a rather large portion of your sales in fees. This is especially true if you are selling big-ticket items. A merchant account comes with a merchant identification number. That is about all it gets you. If you are selling just one or two items on your site you won't have much need for a shopping cart.