[involans]

Trying to explain glottal stops with English examples is pointless - "Apple" doesn't begin with a glottal stop in English; "fear" and "ear" differ only in the absence of /f/.

German does introduce a epenthetic glottal stop before word-initial vowels, but not English.

Also, attempting to explain /ɪ/ as "Fin" -> "fen" is also unhelpful.

[skellystudios]

I've seen it described as the sound or throat action in the middle of "uh oh!".

I found that kinda useful.

[samatman]

At least in my accent, the 'tt' in written is a glottal stop.

[Natsu]

There's a glottal stop between book and case in bookcase, though.