I became fed up with my airpods (and bluetooth earbuds in general) and switched to some great (albeit definitely not new and definitely not high end) IEMs and couldn't be happier. I was worried about losing the noise canceling but it turns out to not matter in the slightest with IEMs with proper tips on them, the isolation is unbelievable. Not dealing with battery life and charging issues anymore is worth it alone. The absurd price difference is a great bonus too.
Yup, it's pretty impressive how good IEMs can be at isolating you from sounds with good fitting tips. I am fond of the SpinFit W1 tips, they were much better than whatever stock tips came with mine and they seal really well.
I got some Comply tips and they're great. Was weary of the idea of foam tips at first. I am pretty used to the feeling of earplugs though and it hasn't been an issue. Frankly they're TOO good sometimes, I've been startled by people trying to get my attention more than once.
What's an IEM?
"In Ear Monitor". Its named for its use by musicians to listen to the mix while they perform, but now it just refers to the style of isolation via mechanical means (foam or silicon seal) and the way the cable folds back over the top of the ear.
* https://en.wikipedia.org/wiki/In-ear_monitor
"In-ear monitor", fancy buzzword for earbud afaict (I am definitely not a part of the audiophile scene and am not sure if there is actually a difference there, except maybe they insert very deep in the ear canal and have excellent isolation).
They're musicians' tools. Playing live music is absolutely destructive to your hearing, and ear protection is required. IEMs are a combination of protective equipment (many are designed the same way as concert earplugs) and earphone, so you can hear a clear signal from the mixing board at a safe volume, while shutting out the house speakers' insane noise levels.
Before IEMs were common, the norm was (hopefully) ear plugs and having monitoring speakers pointed at the musicians from the floor.
IEMs can be made in the concert earplug style, which is usually a center pair with 3-4 layers of rubber domes like typical earbuds. Or you can pay more and have custom molds made of your ears, so ones can be made to perfectly fit.
"Monitor" also has certain implications in audio. Usually something designed for monitoring will have a flat frequency response, while most consumer gear has aggressive EQ curves that do things like boosting bass. (Most people will think monitors "sound bad," while the lack of sound tampering is essential for performance and mixing.)
The term "earbud" usually implies an earphone with no seal, while "IEM" implies one that seals to the ear canal.