Usually something that provides a logical function. 1) Relays and motor starters controlled by outputs (control elements). 2) Switches and sensors connected to inputs (feedback elements). 3) The matrix items of a ladder logic rung, reflecting the results of executing program instructions (ladder logic elements). 4) In a general sense, anything that can be identified as a part of a larger entity — as with a data element being any addressable unit of data as long as it can be identified as a sub-unit of a larger unit of data (a bit as a data element of a word, structure or file; a word as a data element of a structure or file; a structure as a data element of a file).