Could somebody explain to me how the employment verification process works in the UK? Or point me to a place on the internet that would explain it?

Basically, I’m trying to compare employment verification practices in the United States with those in the United Kingdom.

For example, in the United States the social security number is widely and heavily used as the starting point in employment verification. Is the same true in the United Kingdom with the national insurance number, or PAYE number?

Thanks!
Sean Mullins