This conversation is being brought back from the dead due to the overwhelming amount of people who spread false information about lag and lag compensation. Please read the entire article, if you feel the information is wrong or inaccurate comment below.
What is Lag?
For those of you who don't know what lag is or you do not fully understand it here's a brief explanation:
Imagine you are playing a game of TDM. You are sniping and have a man in your sites as he runs across the map. Your crosshair is directly on his chest. You fire, but nothing happens. No hit marker or anything. It's a clean miss. How does this happen.
As an individual player you are playing on your own map by yourself essentially, as is everyone else in your lobby. The host player is the one who communicates where everyone is in their own game and translates that onto your map. Thus making it appear they are right there with you. The host is the central point for all players; your game is a mere reflection of what is taking place in his own space and time. All information is sent to him and all information received is sent from him. The information does not flow as one solid piece though. It is broken up into packets of information interlaced with other packets (eg one bit sent then one bit received, each player getting their own individual interaction with the host at a time) also known as connection speed. In a perfect situation, if his game has a man throwing a grenade then your game will reflect that action. However, if the host player does not have the bandwidth to send and receive packets of information in a sequacious manner then the information will get "bottlenecked" and you then start noticing lag.
Not all lag is cause by the host. Each individual player can cause lag. If little Jimmy is downloading "movies" and decides to play CoD while they download then little Jimmy is only going to affect himself, he will still send information without any problem. But if little Jimmy is uploading something or has multiple devices connected to the internet at one time then he will not be able to send/receive a complete sequence of interactions thus making little Jimmy lag.
This goes for you as well, to limit your contribution to lag you must allow the necessary bandwidth needed to send and receive information without constriction so that the host may too send and receive accurate information to other players.
Going back to you sniping the man running across the map. Based off the information that you have received, it appears that the man running across the map is directly in your crosshairs. However you have not received the update that man has moved. So you are essentially firing at a ghost and you're playing a game based off of information that is inaccurate.
Lag compensation isn't suppose to be noticeable, but when it is it's extremely annoying. So I figure I would shed some light on the matter.
Ever play a match and walk into a room start to shoot a guy clearly 20-30 feet in front of you only to get knifed? You go into an all-caps-rage when you find out this man just lunged at you from 10 yards out. No, he doesn't have the Commando Perk, it's called lag compensation and it does a few different things. The game interprets what is being done and when information is taking too long to update it starts to assume movement patterns. So when you see the guy at the other end of the room that's lag compensation telling you that he is over there when in real time he's been standing right next to you in position to knife. This doesn't happen often as mentioned (or at least noticeably like the situation describes), only when there are gaps in packet transactions.
What Lag Compensation Is Not
It has become a common misconception that lag compensation is the intentional suppression of a one's internet in hopes that it places players on the same connection speed. This is not true, if you're having a bad connection it is probably an instance where so many people in the lobby are having a difficult time connecting to the host himself that everyone is having a hard time communicating. As mentioned above, are several factors that add to lag. If those factors are magnified it can mean the whole lobby suffers
Factors That Contribute To Lag
Now that you have a basic understanding of lag and what it is you might be wondering how lag comes about. Match making is a major factor. When you are placed in a lobby with several people of different nationalities and locations that span the globe your chance of lag is almost assured. Imagine having to send information to someone who lives well over a thousand miles away. If you were doing it by mail it would take many days. When being done by internet it takes several milliseconds. In retrospect that might not seem like a much time, but ask anyone in a fire fight what all happens during a span of 10-15 milliseconds. An SMG with rapid fire can easily put off 3-5 extra rounds in the short amount of time it takes for you send a bit of information to the other side of the globe. Now imagine there are multiple people that live hemispheres away from the host. Those milliseconds taken simply because location compound on top of each other, throwing the game from 2-3 milliseconds off to 10+. You then add that to the already average 10 milliseconds that it takes for your PS3 to process and you to react to what's happening on the screen, that's huge. Now imagine the host has less than ideal internet, or you're playing with little Jimmy. All those factors compounded have now thrown the game off by almost a full second
The wireless world that we live in is pretty sweet. The no-strings-attached lifestyle is extremely convenient. It can greatly affect your gaming experience though. As most of you know a wireless connection is not even comparably as fast as a physical connection. Think about it, you already have to send information from you to the controller, to the PS3, to the modem, to the PSN, to the Host and then it all has to come back to you. Why throw in a wireless router? That's valuable time you have to wait. A router also limits the bandwidth. Most internet providers give you plenty of bandwidth to work with so it's not really a factor, but if you have the cheapest internet package offered those megabytes/s you're losing becomes a much bigger fraction of the problem.
Lag can at time also contribute to glitching. When you are sending information to the host you are compressing information and breaking it up to make the sending easier. It's not uncommon that bit of info can be lost in this process. It is believed that the drop rate of information happens on a regular basis. However, The fact that so much information is being sent and the fact that a single bit can be menial at times makes this unnoticeable or a nonfactor. In times when lag is at its highest point the amount of information dropped, lost, or misinterpreted can be high as well making glitches more frequent
Care Packages falling through
Reloading twice or not reloading at all
KIA by friendly claymores/grenades or surviving claymores/grenades
Spawning in enemy territory
Enemy dressed and labeled as a friendly
Throwing random grenades or equipment not detonating
1) Lag is excessive amount of time it takes for packets of information to be sent and received by and from the host player
2) Lag is mostly caused from less than ideal match making, either because of vast distance in players location or because of connection speeds are poor
3) Lag is not always directly resulting from a poor host. Other players can attribute to lag by not providing a strong connection to the host
4) Your game is a mirror of what the host's game resulting in the host often, but not always, having less lag
5) Limiting the number amount of hardware between you and the host (eg, getting an all-in-one router/modem) as well as reducing the number of devices using internet decreases lag
Q. My connections status is four bars and I'm still lagging, why?
A. The connection status is based off your connection to the host. You are not lagging, the other player/s are
Q. Why am I still lagging when I join a local match?
A. Remember location is not the only factor when lag happens. Internet connection is most likely the problem in these kind of situations.
Q. Does lag just affect hit markers and "lag jumping"?
A. No, lag affects many smaller things often blamed on "glitching" (the processing of misinformation)
This information was gathered from independent research from multiple sources in hopes of providing a better understanding. If you have further questions of would like to correct an error I have made, please feel free to do so and POLIETLY ask. If you find this helpful or useful please comment to bump it