plug in

Yes, definitely. Keep it plugged in as much as you want.

Every few months you may consider running it on battery power for a while. The jury is out on whether or not this is important to keep the battery healthy but couldn't hurt.

 

One school of thought says if it's plug in 24x7 regardless of whether it's in use or not, battery longevity suffers but there is no empirical data.

I leave it plug in if I am going to go back to it repeatedly but pull the plug if it's already 100% charged and I don't intend to use it for a while. 1/2 way between ideology (old maid's tale) and convenience.

 

I believe the computer effectively pulls the plug for you automatically. Notice that most of the time, when the computer is plugged in and you have > 97-98% charge, "About this Mac" reports that the battery is not being charged. I think this is effectively the same as having it unplugged.

Actually, I have wondered how the green/orange light on the MagSafe connector works and it wouldn't surprise me if it's a simple circuit that displays green when the cable isn't delivering any power. Meaning that it's effectively unplugged.

So, basically, I don't think there's any use in unplugging the computer if it's already charged.

And I think there's minimal point to putting wear on the battery by running the computer on battery power unnecessarily.

 

Yes it is. I run my battery down to single digits once per month just because I can, and someone told me once in a galaxy far, far away that cycling the battery in this manner was good for battery health & longevity.

Mine is plugged in the majority of the time, it's one of my desktop machines running in clamshell mode with external peripherals. When I travel it comes with me for work on planes and in airport lounges.