Among the various improvements and innovations that have received the videogames in its history, one of the most important of all has undoubtedly been the inclusion of the online multiplayer, as this new mode managed to completely revolutionize the way we play. As the technology has advanced, the online multiplayer has grown in an impressive way until today, where this modality has reached its maximum capacity and has become a standard within games. The advancement of the online multiplayer also led to the creation of new types of videogames, which exploit online connectivity to the fullest, the most prominent of which are the Massive Multiplayer Online games (abbreviated as MMO) MMOs and MMORPGs can currently accommodate millions of users who are normally interacting with each other simultaneously. However, despite the great popularity and longstanding presence of these online games, many players are still asking how can MMO videogames accommodate so many players in one world? So, here’s how the most important element in the structure of massive online multiplayer games works. First of all, it should be explained that it is exactly a server in online videogames: A server is a specialized hardware that mainly has installed software that stores files and distributes them through the Internet networks, which allows many conventional PCs to make use of such data simultaneously. The servers have the objective of providing useful resources for their users and in the case of online videogames, the servers are in charge of collecting the data generated by each connected player and sending it to the rest of the users immediately so that games can be produced in real time. Having made that clear, the type of server that MMO videogames use are dedicated servers, since they have the necessary resources for the operation, support and management of the large amount of data that each element of an MMO requires. The dedicated servers work independently and are operated by the company that developed the videogame, which allows them to monitor, control and update the content constantly. The MMO games’ Dedicated Server is able to transfer information immediately because it functions as a central antenna that processes and stores data, which is only broadcast to players who require it at an exact time. This reduces the load on customers and makes the most of their resources. Dedicated servers for MMO games are usually divided into two categories: Official Servers and Private Servers. The official servers (as their name suggests) are those owned by the game development company, which usually have unlimited resources. While private servers are the property of third parties that work by obtaining source code that allows them to reproduce the official server of a given game (with considerable limitations), and having done so, the server owner can program his server so that only an exclusive community can access it. Private server owners can even modify the game’s features, and thus get their own version to meet the demands of their exclusive customers. Most MMOs use a primary server that performs the most general tasks of the entire game, and also several secondary servers that host all versions of the same world. That said, it should also be mentioned that MMO games can not only move a world within their servers, but can also influence entire communities to form all kinds of unofficial websites and apps to complement the gameplay of these games and their economy. One of them is the Gaming marketplaces, which are websites specialized in intermediating between buying and selling services or products related to all kinds of online videogames. Among all these websites, one of the most recommended is Eldorado.gg, since it has a comfortable and extremely safe system where any player can market elements of the most popular MMO, such as: sell or buy RuneScape 3 Gold, FFXIV Gil, WoW Gold, among many other types of gaming elements. Having said all this, it is hoped that there has been some understanding of how an MMO videogame works and how it performs its most basic tasks such as keeping a huge number of players in their worlds.