what is called half width at full height amplitude ratio.

I' doing some signal processing, and noticed that when i find a peak i can use the ratio of peak width at full height and the amplitude of the peak as a threshold for my peaks. Basically i'm interested on peaks where energy is concentrated on a narrow time interval. But i don't know if exist some logical explanation to this. I noticed though, that width is calculated for chromatography, but not related to the above mentioned ratio.