Although modern MMORPGs sometimes differ dramatically from their antecedents, many of them share some basic characteristics. These include several common themes: some form of progression, social interaction within the game, in-game culture, system architecture, and character customization. Characters can often be customized quite extensively, both in the technical and visual aspects, with new choices often added over time by the developers. A few games also offer some form of modding in order to allow for even greater flexibility of choice.
Character abilities are often very specific due to this. Depending on the particular game, the specialties might be as basic as simply having a greater affinity in one statistic, gaining certain bonuses of in-game resources related in-game race, job, etc.
The majority of popular MMORPGs are based on traditional fantasy themes, often occurring in an in-game universe comparable to that of Dungeons & Dragons. Some employ hybrid themes that either merge or substitute fantasy elements with those of science fiction, sword and sorcery, or crime fiction. Still others draw thematic material from American comic books, the occult, and other genres. Often these elements are developed using similar tasks and scenarios involving quests, monsters, and loot.
In nearly all MMORPGs, the development of the player’s character is a primary goal. Nearly all MMORPGs feature a character progression system in which players earn experience points for their actions and use those points to reach character “levels”, which makes them better at whatever they do. Traditionally, combat with monsters and completing quests for NPCs, either alone or in groups, are the primary ways to earn experience points. The accumulation of wealth (including combat-useful items) is also a way to progress in many MMORPGs, and again, this is traditionally best accomplished via combat. The cycle produced by these conditions, combat leading to new items allowing for more combat with no change in gameplay, is sometimes pejoratively referred to as the level treadmill, or ‘grinding’. The role-playing game Progress Quest was created as a parody of this trend. EVE Online (which broke almost every MMORPG tradition) trains skills in real time rather than having the player do anything.
Also, traditional in the genre is the eventual demand on players to team up with others in order to progress at the optimal rate. This sometimes forces players to change their real-world schedules in order to “keep up” within the game-world.
 Social InteractionMain article: Social Interaction via MMORPGs
MMORPGs almost always have tools to facilitate communication between players. Many MMORPGs offer support for in-game guilds or clans (though these will usually form whether the game supports them or not).
In addition, most MMOs require some degree of teamwork for parts of the game. These tasks usually require players to take on roles in the group, such as those protecting other players from damage (called tanking), “healing” damage done to other players or damaging enemies.
MMORPGs generally have Game Moderators or Game Masters (frequently abbreviated to GM), who may be paid employees or unpaid volunteers who attempt to supervise the world. Some GMs may have additional access to features and information related to the game that are not available to other players and roles.
Most MMORPGs provide different types of classes that players can choose. Among those classes, players are encouraged to roleplay their characters, providing rules, functionality and content to this end. Some MMORPGs offer “roleplay-only” servers that prohibit interactions to other players among characters for those who want to immerse themselves in the game in this way. Community resources such as forums and guides exist in support of this play style.
For example, if a player wants to play a priest role in his MMORPG world, he might buy a cope from a shop and learn priestly skills, proceeding to speak, act, and interact with others as their character would. This may or may not include pursuing other goals such as wealth or experience. Guilds or similar groups with a focus on roleplaying may develop extended in-depth narratives using the setting and resources of the game world.
Since MMORPGs have so many elements in common, and those elements are experienced by so many people, a common all players, and this has led players of many games to expect “buffing” or “nerfing“, which describe the strengthening or weakening, respectively, of particular game elements. (“Buffing” also refers to in-game effects that temporarily enhance performance; both usages come from a core meaning of increasing power levels.)
As another example, in many older MMORPGs the fastest way to progress was simply by killing the same monsters over and over again, and as this is still common in the genre, all MMORPG players know the process as “grinding“, or “camping” (sitting at a monster’s spawn point in order to attack it as soon as it respawns). The importance of grinding in MMORPGs, and how much “fun” it contributes to the experience, is constantly debated. Many MMORPGs have taken steps to eliminate or reduce grinding. For example, in Tibia, a monster doesn’t respawn if a player is near its spawn point. But few such attempts have met with success, and it is generally accepted by players and developers alike that some amount of ‘grind’ is required to maintain a stable playing experience.