Toyota Repair: battery light, negative battery cable, alternator problem

Question
QUESTION: the belt on my 98 4runner V6 has been squealing for awhile and while driving the other day the light came on then went off. I tightened the belt and noise went away and light was off. I then was driving again and the light came on but went off during the drive, I stopped at a store and when resuming my drive the light came on and now is on all the time , not sure where to start , battery , belt or new alt ?

ANSWER: Which light is coming on?

---------- FOLLOW-UP ----------

QUESTION: Ted the Battery light is the light that is coming on , for instance , i drove it yesterday and within 15 miles the light was on and stayed on , im just not sure where to start , belt , alt ect..

Answer
Most likely an alternator problem which can also be intermittent, here is a quick test you can do, while the battery light is on, with the engine running disconnect the negative battery cable, if the engine dies the alternator is the problem, I forgot to mention the first thing you should do is to make sure the alternator belt is intact.