The network effect is a phenomenon in which the value of a product or service increases with the number of people using it. This effect is most commonly seen in social networks, as the more people use the network, the more valuable it is to each individual user. Additionally, the network effect can be seen in many other markets, such as telecommunications, technology, and financial services. As more people join the network, the more valuable it is to all users, as it creates more opportunities for collaboration and communication.