[X-Istence]

I believe users can also suggest them? I've got a couple on my LinkedIn profile that I didn't add, and weren't there earlier but I got a notification I was endorsed for that skill anyway.

[illuminate]

It's really bizarre, I have skills I've been endorsed for for jobs where I didn't use those skills around the endorsers!

[finnw]

I've had former colleagues offended that I did not endorse them for skills (that I had not witnessed them using, though I knew they used them at that company.)