If I could tell every single developer one thing, it's that there are more people using accessibility settings than they know. A huge chunk of users have the text size turned way up, are using screen readers, or can't get the sound the way the dev intended.

But I'd also like to tell everyone that regex can save them so much effort.

Oooooh oooh I'd also like to teach them a simple Unix search...

Okay, what's one thing YOU would tell every single developer, senior or junior, in the tech industry?