What exactly does a primer do? And when in your skin care routine do you use it?

[Wenchelda]

Am I right in thinking a primer somehow helps to keep your make up on? I've tried many different foundations but no matter which one, after a couple of hours they never look the same. Is a primer what I need to help it stay in place?

If so, at what point in my routine do I use it? Right before foundation? At the moment I do cleanse or face wash - toner - serum - eye cream - BB cream - foundation (or leave the foundation off some days). So would I just add the primer In between bb cream and foundation? Or would I not need the bb cream? It just normal moisturiser instead? Thanks

I cleanse then eye cream then primer then face paint it really helps my make up last all day. I dare say everyone will have a different routine though
I won't be without primer now.

It should help make up stay on longer. It will also mattify, fill open pores and fine lines (polyfiller for the face) and 'soften' the face (like soft focus on a camera almost).
I'd apply after creams and before makeup.