The noticeable effects of lag vary depending on the exact cause, but also on any and all techniques for lag compensation that the game may implement (described below). As all clients experience some amount of delay, implementing these methods to minimize the effect on players is important for smooth gameplay. Lag causes numerous problems for issues such as accurate rendering of the game state and hit detection. In many games, lag is often frowned upon because it disrupts normal gameplay. The severity of lag depends on the type of game and its inherent tolerance for lag. Some games with a slower pace can tolerate significant delays without any need to compensate at all, where as others with a faster pace are considerably more sensitive and requires extensive use of compensation to be playable (most prevalent is probably the first-person shooter genre). Due to the various problems lag can cause, many players that have a lower speed Internet connection are often not permitted, or discouraged from playing with other players or servers that have a distant server host or have high latency to one another. Extreme cases of lag may result in extensive desynchronization of the game state.
Lag caused by an insufficient update rate between client and server can cause some problems, but these are generally limited to the client itself. Other players may notice jerky movement and similar problems for the affected client, but the real problem lies with the client itself. If the client cannot update the game state at a quick enough pace, the player may be shown outdated renditions of the game, which in turn causes various problems with hit- and collision detection. If the low update rate is caused by a low frame rate (as opposed to a setting on the client, as some games allow), these problems are usually overshadowed by numerous problems related to the client-side processing itself. Both the display and controls will be sluggish and unresponsive. While this may increase the perceived lag, it is important to note that it is of a different kind than network-related delays. In comparison, the same problem on the server may cause significant problems for all clients involved. If the server is unable or unwilling to accept packets from clients fast enough and process these in a timely manner, client actions may never be registered. When the server then sends out updates to the clients, they may experience freezing (unresponsive game) and/or rollbacks, depending on what types of lag compensation, if any, the game uses.
Lag due to network delay is in contrast often less of a problem. Though more common, the actual effects are generally smaller, and it is possible to compensate for these types of delays. Without any form of lag compensation, the clients will notice that the game responds only a short time after an action is performed. This is especially problematic in first-person shooters, where enemies are likely to move as a player attempts to shoot them and the margin for errors is often small.