What is this markup icon and how/when to use it?

[Mac_i_Am]

Masquerading as a pencil, what does it do? Does it have a name? Why do I hate that apple doesn’t explain it anywhere

open a photo > Edit > click the little marker icon on top

 

[chabig]

That's the lasso tool.

Use Markup on your iPhone, iPad, or iPod touch - Apple Support

With Markup, you can edit screenshots and photos, select different opacity and font thickness, and even add a signature to a PDF document.

support.apple.com

 

[Mac_i_Am]

Thx for looking that up!