A smart mob is a collection of assembled people working together through the use of information technology towards some purpose. These mobs come together for a wide variety of reasons, including everything from political protests to watching celebrities, or even just for the purpose of delivering elaborate practical jokes. The ability of the mobs to communicate and organize spontaneously has added a new dimension of effectiveness never seen before in spontaneous crowd behavior, and this has had many serious implications for society, even playing a role in the toppling of some governments. Sometimes a smart mob is something that happens in an organic way without any particular planning, while at other times, it may be more organized, but in either case, the behavior of the mob will be generally more intelligent than a normal crowd of people.

According to historians, crowds of protesters and other groups of people have always had the potential to cause political change in societies. Over the course of history, there have been major riots and other events that have brought a lot of attention to serious issues and led to huge disruptions in the political landscape. Since the mobs weren't well-organized, they were generally defenseless against authorities who could communicate and coordinate with each other, and this made the groups easier to handle from the perspective of governmental regimes. The development of modern communication technology has changed this dynamic in a number of ways.

A smart mob will generally rely on a variety of technological tools to work in a coordinated way. These include cell phones for talking and text messaging, along with computers equipped for Internet access. Much of the planning often happens on various social networks on the Internet, and then in the midst of a protest or event, the mob can act instantaneously to any change based on communication through portable tools like cell phones. This ability to communicate without distance or time constraints can make a smart mob very agile. For example, if one part of the mob notices that police are headed in a certain direction, they can warn the rest of the mob so that they can disperse before the police ever arrive, simultaneously planning to meet up somewhere else and continue their activity.

Sometimes a smart mob is totally unplanned and happens in an organic way. For example, if a shopper is in a store when someone announces a surprise sale, and he or she texts a companion elsewhere, it can lead to a chain reaction. Within minutes, a whole mob of people may descend on the store, all of them looking to buy the item that has been discounted. This sort of spontaneous behavior often leads to mobs of people surrounding or chasing celebrities who were initially only spotted by a single person with some sort of communication device.