An expression used in online retailing to describe the Monday following U.S. Thanksgiving weekend. Cyber Monday is generally thought of as the start of the online holiday shopping season. Similar to Black Friday, (the unofficial start of the holiday season for offline businesses), online retailers will usually offer special promotions on this day.

Also known as "Black Monday".

There are a couple of theories as to why online sales increase on Cyber Monday, although some debate whether all retailers experience the same trend. One theory suggests that people see items in the shopping malls over the weekend and wait until Monday to buy them online, where they can compare prices, avoid lines and/or take advantage of free shipping or other offers. Another theory states that people have faster internet connections at work and, therefore, wait until then to make online purchases.