Put EQ in windowed mode by hitting alt+enter. Doubleclick the EQ icon on your desktop and start up another account. Ta da!
Boxing, to me, doesn't really capture the spirit of the game. Maybe I'm just not that good at multitasking - even with macros and hotkeys and a programmable Razer Black Widow and a programmable Razer Naga - it feels like more work than it's worth. don't get me wrong - I really like the convenience of having a FULL toon to support me instead of a J1 mercenary but the mercs are "almost" good replacements...at least until the upper levels or the "real" game.
The number is the number of accounts played by one person at a time. And you can use multiple computers as well. Back in the old days, when 2 boxing per computer was the norm, people often 6-boxed using 3 computers. I don't think as many 6-box any more, but there are a few that still do it, but I think they 3-box on 2 computers now-a-days. My computers are old, and generally only 2 box on one, if I do at all, but have 3-boxed before where I needed the toons for something. 3-boxing is horrid if I'm actually playing all 3 accounts, but I've never tweaked it out for boxing, as it does ok on 2-boxing once I've been playing for a while. I hear the 3rd party programs like [Unmentioned 3rd Party Software] and is it called WinEQ? are both great and make boxing alot easier. Although Brohg's answer was more concise, I thought I'd through in some verbage in case Brohg's answer didn't confuse you! Yther Ore.
It is where you have more than one account controlling them at the same time. I have been a two boxer working on a third account. Benefits: You bring your own group and can get a lot done when you log on. Can setup buffs from within your accounts. Can setup porting within accounts. Can have the accounts allow you to request missions with a min group requirement. Cons: You are controlling multiple accounts so, it is harder to talk. You bring your own group so search for people LFGs which deceased/eliminates the social aspect of the game. You kill PUGs. With boxing, you get proficient in working your group. You do not get to experience those wild, out of control groups and miss some good memories. Rykard