Wikipedia:

Electronic commerce, EC, e-commerce or ecommerce consists primarily of the distributing, buying, selling, marketing, and servicing of products or services over electronic systems such as the Internet and other computer networks.

The information technology industry might see it as an electronic business application aimed at commercial transactions. It can involve electronic funds transfer, supply chain management, e-marketing, online marketing, online transaction processing, electronic data interchange (EDI), automated inventory management systems, and automated data collection systems.

It typically uses electronic communications technology such as the Internet, extranets, e-mail, e-books, databases, and mobile phones.

What to check for on your competitors' websites

• Product Catalog:
  • database listings, keywords, descriptions, price.
• Product Shopping Cart Interface
• Payment Modalities (currencies, credit card, Paypal etc.)
• Customer Service Modalities (i.e. intranet. Fedex parcel follow up etc.)
• Delivery Modalities
• Affiliate Programs (Amazon, Chapters etc.)
• Games, Contests or special offers