Primer is a makeup base applied after skincare but before foundation. It creates a smooth canvas for makeup application and helps it last longer.

Primer fills in pores and fine lines, creating an even surface. It also controls oil, hydrates skin, and helps makeup adhere better, preventing fading or creasing.

This question is outside the scope of beauty advice. The focus here is on makeup primer.

While moisturizer hydrates, it doesn't necessarily prep the skin for makeup like a primer. Primer provides a smooth, even surface and enhances makeup longevity, which moisturizer alone may not achieve.