[wil421]

A quick Wikipedia search turns up more fields [1]. Although some of these fields are not 100% accurate due to historical reasons (I'm looking at you IE). I'd bet there are a couple other data points they gather via JS to finger print.

Example:

Mozilla/5.0 (iPad; U; CPU OS 3_2_1 like Mac OS X; en-us) AppleWebKit/531.21.10 (KHTML, like Gecko) Mobile/7B405

1. https://en.m.wikipedia.org/wiki/User_agent

[gruez]

I compared 2 chrome versions and it seems that most of the version numbers there are static.

    Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2979.0 Safari/537.36
    Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.10 Safari/537.36

As for iOS 10 it's pretty sparse as well.

    Mozilla/5.0 (iPhone; CPU iPhone OS 10_0_1 like Mac OS X) AppleWebKit/602.1.50 (KHTML, like Gecko) Version/10.0 Mobile/14A403 Safari/602.1

It's slightly worse than windows because it probably discloses your device type, but there are tens (hundreds?) of thousands of users for each iphone variant.

[wil421]

Good read here.[1] An example could be using your installed fonts. Like I was saying they probably use a bunch of other JS tricks. These 3rd parties aren't going to disclose anything.