Spiders construct a wide variety of silk structures, ranging from draglines to prey capture webs. Spider silks rank among the toughest materials known to science, and these material properties are critical for understanding how silk structures, such as webs, function. However, the mechanics of spider silk are often ignored in the study of webs. This review aims to show how the material properties of silk proteins, the structural properties of silk threads, and the architectures of webs ultimately interact to determine the function of orb webs during prey capture. I first provide a brief introduction into spider silk and how to characterize its material and structural properties. I then examine the function of draglines as “lifelines” to provide a well-understood example of the interaction of material and structural properties in silk function. Next, I examine how orb webs function in prey capture by first intercepting insects, then stopping their kinetic energy of flight, and finally retaining the insects long enough to be subdued by spiders. I show how variation in the material and structural properties of silk acts synergistically to facilitate the stopping and retention potentials of orb webs, and why this can occur in opposition to how orb webs intercept prey. Finally, I summarize why information on the material properties and structures of silk threads needs to be better incorporated into future investigations of spider webs in general.