Cameron P. answered 23d
Web Developer and Teacher with 2+ Years of Teaching Experience in CSS
Bootstrap follows a BEM-inspired naming convention using hyphens. This convention isn't full BEM however, as it's more of a pragmatic hybrid balancing both readability and utility.
The general style is lowercase letters, words separated with hyphens, and not using underscores or camel case.
Bootstrap occasionally mimics the BEM (Block-Element-Modifier) structure as I alluded to.
Many of Bootstraps utilities are single-purpose, often patterned as [property]-[value].