the.com/vital
The stuff you only notice the moment it stops.
means Absolutely necessary for life, or so important that something fails without it.
from From Latin vita, life, via vitalis, meaning of or pertaining to living itself.
Vital signsPulse, breath, temperature: your body's status bar.
Vital statisticsBirths, deaths, marriages, tracked by governments since 1538.
Same rootVitamin, revitalize, and vitality all descend from vita.