It was developed by John Brooke[1] at Digital Equipment Corporation in the UK in 1986 as a tool to be used in usability engineering of electronic office systems.
However, it can be argued that given a sufficiently high-level definition of subjective assessments of usability, comparisons can be made between systems.
Because it yields a single score on a scale of 0–100, it can be used to compare even systems that are outwardly dissimilar.
Recently, Lewis and Sauro[3] suggested a two-factor orthogonal structure, which practitioners may use to score the SUS on independent Usability and Learnability dimensions.
Bangor, Kortum and Miller[5] have used the scale extensively over a ten-year period and have produced normative data that allow SUS ratings to be positioned relative to other systems.
Based on a review of hundreds of usability studies, Sauro and Lewis[6] proposed a curved grading scale for mean SUS scores.