An oscilloscope is an electronic instrument that is used to represent the voltage of an electronic device. It signifies one or more electric potential differences in a clear two-dimensional graph, with the horizontal axis representing time and the vertical axis showing voltage. It is used to diagnose the working condition of any electric equipment.

There are basically two kinds of oscilloscopes: analog and digital. Digital oscilloscopes use analog-to-digital converter for converting the measured voltage into digital data. The digital oscilloscope collects waveforms in the form of samples, which is then displayed on the screen when it has accumulated enough samples. Digital oscilloscopes have higher data processing capabilities.

Digital oscilloscopes are further categorized into: digital storage oscilloscopes, digital phosphor oscilloscopes and sampling oscilloscopes. A Digital storage oscilloscope is just a conventional digital oscilloscope. It displays on a raster-type screen instead of luminous phosphor. The waveform information in a digital oscilloscope can be stored, archived, analyzed and printed by the oscilloscope or by a computer attached to it. One thing that differentiates digital oscilloscopes from analog ones is that, there is permanent signal storage and extensive waveform processing. Digital storage oscilloscopes are perfect for applications that involve single-shot, high-speed, multi-channel design or low-repetition-rate.

Digital phosphor oscilloscopes are an advanced version of the digital oscilloscopes. They have unmatched acquisition and display capacities. They can reconstruct a signal very accurately. They use parallel processing architecture unlike digital storage oscilloscopes that use serial processing architecture for capturing, displaying and analyzing signals. Digital phosphor oscilloscopes rasterize waveform data and copy it to the display memory without any processing bottlenecks. A digital phosphor oscilloscope is perfect for digital debugging of intermittent signals, communication mask testing, repetitive digital design and timing purposes.

A digital sampling oscilloscope is used for capturing signals for which the frequency components are much higher than the oscilloscope's sample rate. This oscilloscope can capture very fast signals, and also attain very high bandwidth and high-speed timing for repetitive signals. However, a digital sampling oscilloscope's has a limited dynamic range to around 1Volt (peak-to-peak). Even the safe input voltage is very limited at 3 V as compared to 500 V for other oscilloscopes.

Agilent, B+K Precision, EZ Digital, Extech Instruments Corp., Fluke, Instek, International Tools & Technologies, Inc., Iwatsu, Kenwood TMI Corp., LeCroy, Morrow Wave, Tektronix and Yokogawa are some of the popular digital oscilloscope manufacturers. Information about digital oscilloscopes, along with their prices and product facts can be sourced from the internet. There are hundreds of websites that give information about oscilloscopes.