When I turn the key to start my 4runner, I hear a loud clicking noise coming from my starter. The car doesn't turn over normally but had a few times that I've tried including once when I drove it home from work, 2$8@3 I drove the lights flickered, radio turned on and off, antenna was extending and retracting wildly, and dash lights were flickering. Recently my alternator belt has been squeaking and I was getting ready to change that not sure if that helps at all, my terminals on my battery aren't perfect but they aren't corroded to the point where I think that'd be a problem, I recently had an aftermarket stereo put in.
My car has 160000 miles.
A starter like any other mechanical and electrical part is subject to failure sometimes for no apparent reason. However, sometimes this is misdiagnosed as well and often mistaken for something much more simple like a fuse or starter relay.
The starter relay is a small unit near the starter that directs power to the starter from the battery. When this fails, it may cause a clicking sound and will not allow the starter to engage the flywheel when you turn the key. I would suggest having a professional mechanic, such as one from YourMechanic, come to your home or business to inspect the clicking and the starting issue.