Shared proxies can be used by multiple people at the same time. Often there can be from 3 to 5 users, it all depends on the conditions of a particular proxy service. The main disadvantage of such proxies is the presence of "neighbors" simultaneously using the proxy server. This is fraught with getting such proxy IPs into spam and block lists, blocking by services as a result of the actions of your neighbors, as well as drawdowns in data transfer speed. The main advantage of a shared proxy is its relatively low price, unlike private and dedicated proxies. This type of proxy is suitable for non-critical tasks, where you can ignore the risks of blocking.