hanging apps after attempt to close them.

[AllaN01Bear]

im a mac driver . but mac has a unix filesystem called darwin which is a watered down version of berkley dsb which is a unix based os. i re learned a important lesson today. my webrowser refuses to close when i dismiss it . so , in this case , goto terminal, type killall, one word , and the name of your feisty app. bing, done .

[emulatorloo]

1. See also "How to force an app to quit on your Mac"

For folks like me who are to lazy to mess w terminal:

Press these three keys together: Option (or Alt), Command, Esc (Escape).

Or choose Force Quit from the Apple menu  in the corner of your screen.

More here:

How to force an app to quit on your Mac
https://support.apple.com/en-us/HT201276

[usonian]

2. You can also fire up activity monitor, click on an app and quit it.

Just for clarity, the OS is Darwin, the filesystem changed (it was transparent to everyone) from Mac OS Extended (HFS+) to APFS. (SURPRISE) right under our noses. It's just not backward compatible earlier than 10.13 High Sierra that I know of.

https://www.howtogeek.com/331042/whats-the-difference-between-apfs-macos-extended-hfs-and-exfat/

Darwin is based on BSD.

Intel apps run on Apple Silicon (M1 and M2 chips to date) via "Rosetta" emulation and it works well for me.
Old-timers will remember when an early version of Rosetta ran PowerPC apps on Intel CPU's.

Motorola MC68000 -> PowerPC -> Intel -> Apple Silicon (ARM)
Rosetta doesn't come installed with newer Macs but is a free download from Apple. Not sure why.
https://en.wikipedia.org/wiki/Rosetta_(software)

Edit to add:
https://opensource.apple.com

Open Source projects at Apple. Limited.