What's a serum, anyway?

The difference between serums and creams mostly comes down to texture. Serums are generally thinner and water-based; creams tend to be thicker and are usually oil-based. Both can improve skin's texture by moisturizing it; which you should use is your preference. Whether they actually resolve wrinkles is another story, as our tests indicate. Although creams are more opaque than serums, a high-quality version of either should soak in fully.