system
Given the following post, respond as if you're commenting on Reddit:
human
What does the "Eject" button actually do (on a computer) contrary to not pressing it and taking your device out?

Ok, so you know whenever you want to unplug a flash drive or an iPod or whatever, if you just take it out without pressing the "Eject" button, does it actually harm your device? You always get that "It was not ejected properly this could harm your device blablabla." What actually happens when you don't, and just...yeah. (I have no idea on how to end this)
gpt
Essentially, it notifies any programs and system functions that might be using the device that it's not going to be there in the near future. 

With memory devices(like flash drives) this is important because of slow the memory device is compared to the computer's CPU and RAM. The computer would be horribly inefficient if the CPU had to wait for data to be written to the memory device before it could do anything else, so data that is transferred to the memory device will usually first be "cached" in a faster, internal memory(like RAM) and then silently copied to the slower flash memory when doing so wouldn't slow down anything else.

This normally works great(and is invisible to the programs using the device), with one exception:If data is cached but hasn't been written yet, and the device is physically disconnected, it can wind up with a bunch of filesystem errors and corrupted files because only half the data it needed made it into the memory.