Systematic errors originate in instruments, either through incorrect usage, data handling, or with an offset. Systematic errors generally affect all measurements made with the instrument, not just one datum from the experiment.
Random errors, on the other hand, are from unknown or unpredictable sources and often have Gaussian distributions.
Both sources of error are important. Having a base line for your experiments helps identify systematic errors and random errors.
Both of these errors can affect the accuracy and precision of a measurement.
