There are a few topics that "sometimes" creates some pretty heated discussions on other forums, and Foiling is one of them.
Here, we're all one big happy family.
For the new members, don't forget, you can do a search on "foil" and you'll bring up some interesting reading.
Ah, Foiling. Woodburner described the process.
I don't normally use it. Sometimes I do (for really large smokes and holding).
Mostly I don't and there is a time to use a crutch and a time not to and that's about as wishy washy as I can get
Some see it as a crutch, why put something in a smoker and then cover it up, hiding any more smoke (the outside of the meat can still get smokey, but the smoke won't penetrate any more than it has once it reaches 140). If you trap moisture (by wrapping in foil) then you can describe it as "steaming" because the temp of steam is 212 and you're smoking above that.
Others, including Championship Teams, swear by it. Although....most of those that do use it, take the items out of the foil near the end and cover it with a mop/sauce.
Let the discussions begin.