The digital Vernier caliper (more precisely called a digital caliper, since it may use capacitive linear encoding rather than a true Vernier scale) represents the modern evolution of the standard Vernier caliper. Instead of requiring the user to visually interpret the alignment of two scale graduations, the digital caliper displays the measurement directly on an LCD screen, typically to a resolution of 0.01mm (0.0005″) or better. This eliminates the most common source of measurement error with traditional Vernier calipers — misreading the scale — and dramatically reduces the time needed to take and record measurements.
The measurement mechanism in most digital calipers uses a capacitive linear encoder: a pattern of conductive plates on the sliding jaw interacts with a pattern on the fixed beam, and as the jaw moves, the changing capacitance is processed by a microchip to determine position. This system is robust, requires very little power (typically a single CR2032 button cell battery lasting a year or more of regular use), and is accurate to within ±0.02mm or better for quality instruments. The zero/reset button allows the display to be zeroed at any position, which is extraordinarily useful for comparative measurements — you can zero the caliper on a reference part and then measure how much larger or smaller subsequent parts are relative to that reference.
Digital calipers also typically feature metric/inch switching, which allows the same instrument to display measurements in millimeters or inches with the press of a button — extremely useful in environments where both unit systems are in use. Higher-end digital calipers include a data output port (usually a mini USB or proprietary connection) that can transmit measurements directly to a computer, SPC (statistical process control) software, or data logger, eliminating transcription errors in quality control workflows.
The main vulnerabilities of digital calipers compared to standard Vernier types are the dependence on battery power, susceptibility to coolant and chip contamination in machine shop environments (though IP-rated waterproof versions are available), and the potential for electronic failure. For most users in most environments, however, the speed, ease of reading, and versatility of digital calipers make them the preferred choice for everyday precision measurement.