What 29 CFR 1910.23 requires (plain English)
29 CFR 1910.23 sets the requirements for ladders in general industry: portable, fixed, and mobile ladder stands and platforms. Ladder falls are a persistent cause of serious injury, and the standard covers how ladders must be built (load capacity, uniform rungs, slip-resistant surfaces), how they must be used (one person at a time as designed, not overreaching, kept in good condition), and how tall fixed ladders must be equipped for fall protection.
The general requirements apply to all ladders: they must support the maximum intended load (portable and mobile ladders generally to at least four times that load), have rungs, steps, and cleats that are parallel, level, and uniformly spaced, use slip-resistant surfaces, and be kept free of defects; a ladder with a structural defect must be removed from service until repaired. Ladders may be used only for the purpose for which they were designed. These design-and-use rules are the everyday core of the standard.
The most significant modern change concerns FIXED ladders. Under the companion sections 1910.28 (duty) and 1910.29 (criteria), fixed ladders that extend more than 24 feet above a lower level must be equipped with a personal fall arrest system or a ladder safety system. The old reliance on cages and wells is being phased out: fixed ladders installed on or after November 19, 2018 must use a personal fall arrest or ladder safety system, and ALL fixed ladders over 24 feet must be so equipped by November 18, 2036. A cage alone, once the standard solution, is no longer considered adequate fall protection for a tall fixed ladder.