Throw and flood are terms used to describe the weapon light’s beam pattern. Throw refers to the light’s ability to project light over distance, where flood describes the ability to illuminate a large area. Based on your individual needs, throw or flood will be a priority. For example, my everyday carry pistol will most likely be used indoors or in close proximity, so prioritizing a light with a generous flood that will illuminate a broad area is beneficial.  If I was still patrolling both urban and rural environments, pistol lights with better throw that can reach across multiple yards or into a wooded area would be more beneficial. Pistol lights usually prioritize one of these attributes more than the other, but there are products like the Modlite PL350 that provide both throw and flood in the same light.