An eye diagram is a graphical representation of the quality of digital signals. It shows the signal's amplitude, timing, and noise margin. There are several synonyms for the term "eye diagram" that are frequently used in different fields, including "eye pattern", "signal eye", "eye mask", and "bit error rate tester (BERT) plot". Eye patterns are commonly used in telecommunications to evaluate the quality of digital signals, while eye masks are used in signal processing and testing. A BERT plot is a particularly useful tool in electronics testing because it allows engineers to evaluate multiple properties of a digital signal, including its data rate, signal-to-noise ratio, and rise time.