1. A photo on your cv. Or it goes in the bin.
2. Birth date.
3. Marital status and children.
4. Every educational achievement documented officially since highschool.
5. Every working position with an official written reference, in deeply codified form, written mandatorily by your boss, who probably inspired you to want a new job in teh first place. The last company I left had a secret ten factor 5 level numeric rating system, which was then translated into the codified text by the personel department.
I've never understood why this isn't outright illegal. There's literally no reason for it but to discriminate.
At some point earlier in my career I sometimes did a hundred interviews in a week to hire a dozen people. To decide between different people, it was useful to have the pictures attached in application letters.
Of course, in addition it can be used to discriminate.
Those are also obvious things that allow discrimination, but I can't think of a reason why they would be of interest to my employeer.
EDIT: sorry this sounds a bit adversarial, but it was meant as a genuine question.
If the only thing that mattered was individual merit and experience, we could all just sell our work to businesses without a hiring agreement.