In an effort to make PLCs easy to program, their programming language was designed to resemble ladder logic diagrams. Thus, an industrial electrician or electrical engineer accustomed to reading ladder logic schematics would feel comfortable programming a PLC to perform the same control functions. (All about circuits)

Traditionally, ladder logic has dealt only with discrete values and counter/timers, but the ladder diagram today also supports mathematical operations using function blocks. (Control Engineering)

One common development platform is called ladder logic. Ladder logic is a programming language based on executing commands on a line-by-line permission system. Each ladder logic program comprises one or more ladder logic statements. (electronic manufacturers)