“Cart abandonment” isn't a term that any e-commerce store owner wants to hear. It refers to the practice of shoppers abandoning their shopping carts during the checkout process. There are a number of reasons they might do this, but the most common one is that the checkout process is too long or difficult.
From a marketing standpoint, you're going to want to gather as much information on your customers as you can—and checkout is the time to do it. The more information you have on them, the better you can market to them. But collecting this information is a balancing act. Too much information could potentially drag the checkout process out and prompt your shoppers to simply give up and shop somewhere else.
Typically, the best course of action is the following:
Throughout the first step or two of the process, you can still offer other products that you think the shopper may want. I wouldn't push it much past that, however, or you could drive your customers away. You should also give shoppers the option of creating a user name and password accessible account so that the next time they want to make a purchase with you, they won't have to fill this information in all over again.