Re: I don't listen to Led Zeppelin... introduce me!
In the studio a band can take their time to get the material just right. They also have the ability to go back and edit the material until it is perfect. They have the ability to edit it live as well, but it is limited. A live performance shows what they are made of. This band was made of the best material out there.
I have been listening to "How the West Was Won." It came out in May 2003, from concert material from 1972 tour in California. This is really a good introduction to the band. Jimmy Page considers Led Zeppelin to be at their musical peak at this point. This is the best live recordings of Led Zeppelin, in my opinion.
The other live album is from 1973 tour, The Song Remains the Same. From NYC, Madison Square Garden, where they got robbed at the box office. They made a movie of this tour, but it is not as good as the previous year's tour. By the way, I was at the concert that night they got robbed at the Garden.
There is another set of live shows, the BBC Sessions. It was material from four different 1969 BBC sessions, and 1971 Paris Theater in London.
From these live recordings, you can see how the band progressed, and how good they were live.
I am not here just to keep the beat; I add color, timbre, and presence.