Hsl, rgb, lab… those are methods to describe a point in a colour space not the profile in itself.

It might help to think of HWB as if you were a child playing with tempera colors.

Which color do you like? Pick a color tube (H).
Do you want it lighter? Add more white (W).
Do you want it darker? Add more black (B).
Did you mix white and black together in equal parts? Well, now you have to paint your cute rabbit grey, I’m sorry.

Compared to HSL, I feel HWB is actually more concrete, and thus easier to grasp.

Why do we have color profiles, and why can’t we all just expect #FFF to be the whitest white, and #F00 to be the reddest red, etc.

I discovered this accidentally. I was frustrated and wanted a transparency without having to convert HEX to rgb and add the A so I just added 44 at the end of my hex and Bam! transparency! Quickly, I discovered it works with short code too! #fff8 works the same as #ffffff88. I don’t know when this began, but I have been using it ever since!

Also note that you can use shorthand, e.g. #fc08 (rgba), which comes out like #ffcc0088 (rrggbbaa)

That confused me too. I’ve been using RGBa for aeons. Am I misinterpreting something?

Yes, using the four-byte hex has been around for a while. But there has been no way to add alpha to a declared hex color in, say, a custom property before the new relative syntax. You could with the rgb/hsl color functions and custom properties.

wow this is crazy

I think we’ve been able to use an implied 4th channel for a long time:
#f06d0688 will give you the colour with a transparency. With 00 being fully transparent, and ff being fully opaque.

And.