It is the net gamers worst nightmare! The proper word for ping or lag is latency. Latency is the time delay between which packets (bundles) or data are sent between your computer and the server that you are connected to, it is measured is milliseconds so a ping of 200 means 200 milliseconds. In real life that's nothing, less than a second of time but for net gaming milliseconds seem like years!!
   The higher the latency, the higher the time delay and thus the longer it takes for the packets of data to be sent between you and the server.
   The result of this is a high ping and what net gamers call lag, you might people say:

' I have a high ping and lots of lag '

   They basically mean the same thing, with a high ping playing a game on the net it impossible to enjoy, you will find yourself freezing and not being able to move, people will be in front of you at one point then behind you the next in the flash of a second, you will not be able to kill people because you will be firing at 'ghosts' - you think the person is in front of you but by the time the next packet of data arrives at your pc he'll be gone and you will probably be dead.

What is considered to be a good ping?

   A good ping is anything below 200, a brilliant ping is anything below 100. If you have a ping in the 100/ sub 100 region then you have nothing to worry about. A ping of 150 - 230 is perfectly playable, anything above that and you ill find yourself experiencing the problems mentioned above.

How do I lower my ping?

   If you are serious about online gaming then owning a 56k modem or faster will lower your ping. A 56k can achieve a ping varied between 130 - 250. If you are rich and can afford it then buy a ISDN or Cable adaptor and you will find yourself with pings below 100 and your lag troubles will be gone.
   If you already have a 56k modem and find your pings are still very high then make sure you have done the following:

• Have updated to V.90 connection protocol.
• Have the latest modem drivers installed.
  
  
• If it is a Winmodem, throw it in the bin and buy a proper MODEM, Winmodems were designed to work in the windows environment and even at 56k speeds they are absolutely crap for net gaming.

   There are many more factors that may affect your ping, mainly your connection to the net. Make sure you have got a good ISP which offers fast connections. A bad ISP which offers very little bandwidth will mean data packets take longer to send between you and the server, remember its not just you using the ISP, thousands or even millions of others are using it to, taking up space (bandwidth) and thus your ping will always be high even if you have a fast 56k modem.
   For the full lowdown on optimizing your modem and system settings check out Tweak3D's Modem Tweak guide.
  Also, games have their own changeable settings which can improve your ping for that particular game. Quake 2, Half-Life and Sin all use practically the same game engine and this can be configured and optimized the same ways through placing settings in a file known as the autoexec.cfg found in the game folder. For a easy autoexec.cfg creator use Tweak3D's Autoexec creator which will create you own customized autoexec file for Quake 2, Half-Life or Sin. Every setting is explained and can be changed with the click of a mouse. It is amazingly easy and believe me it helps lower ping. 

   Below is how my modem ping has changed since I have bought a new modem and tweaked the autoexec file for Half-Life:

• Using a USR 33.6 x2 Winmodem, NO V.90.
  Half-Life autoexec.cfg unchanged.
  No modem or system optimizations made.
  Ping: 340ms average
  
  
• Using a USR 33.6 x2 Winmodem with V.90 support.
  Half-Lfie autoexec.cfg unchanged.
  No modem or system optimizations made.
  Ping: 280ms average
  
  
• Using a USR 33.6 x2 Winmodem with V.90 support
  Half-Life autoexec.cfg optimized.
  Modem and system optimizations from Tweak3D made.
  Ping: 250ms average
  
  
• Using a Diamond Supra Express Pro Internal 56k Flex V.90 modem
  Half-Life autoexec.cfg unchanged.
  No modem or system optimizations made.
  Ping: 205ms average
  
  
• Using a Diamond Supra Express Pro Internal 56k Flex V.90 modem
  Half-Life autoexec.cfg optimized.
  Modem and system optimizations from Tweak3D made.
  Ping: 170ms average

   By the end my ping has dropped from a 340ms average to a 170ms average. A drop of more than 100ms!

Conclusion?

   Buy a Diamond Supra Express 56k Flex V.90 modem. It has had some great reviews and is dead cheap - £35 inc. VAT in the UK. If you can afford it then buy a Cable modem or better yet wait for ADSL to arrive and use one of them! Tweak your modem and system settings, try out different settings and see which one works best for you. Find yourself a good ISP that supports V.90 and offers lots of bandwidth and fast connection speeds. Tweak your game settings to optimize your connections to servers.