2000 Mazda Protege - Alternator or battery

Headlights going dim and wipers going at slower rate than usual while driving in rain
Car died and had to be boosted off four times before being towed to destination. Is this alternator or bad battery?

it could be either. you should first get the battery tested. a lot of auto parts will do this for free if you bring the battery their. or if you have a multmeter…
How to Test If Your Car Battery or the Alternator Is Bad? (itstillruns.com)

Part 1 -Testing a BAD Alternator: Symptoms and Diagnosis (easyautodiagnostics.com)

Yes! Bad battery, bad alternator, or both.
If battery was bad you may have now damaged you alternator.
If alternator was bad your battery has been severely discharged and may no longer hold a charge.

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If this is happening primarily in the rain, your serpentine belt may be slipping.

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It could also be a bad ground. Dirty battery connections can also cause this. To a lesser extent, a bad connection at the body to engine ground, body end.

A backyard method for testing the alternator. Turn the key to the RUN position. (engine not running)
Touch the alternator pulley with the tip of a screwdriver. You should feel a magnetic attraction at the screwdriver tip. If so, this should mean the alternator is good.

After that, check cable connections and if necessary the connection between the alternator and battery. There should be a fusible link (part of that alt/batt connection) inside the underhood fuse/relay box and should be high amperage. Check all of them.