Yaesu FT-707 ALC question

[Clark]

Hi Folks:

I just purchased a Yaesu FT-707 HF rig, and I'm trying to get
familiarized with each function of the rig.

What exactly does the ALC do? I'm assuming it's some sort of
limiter, but is it used only when 'tuning up' a rig? Or is it common
practice to use it at all times? Does the ALC limit my power output
in any way?

Thanks for your help.

73's

Clark
KB9SJD