The trigger is a key element of an oscilloscope. It captures specific signal events for detailed analysis and provides a stable view on repeating waveforms. Since its invention in the 1940s the oscilloscope trigger has experienced continuous enhancements. The fully digital trigger of the R&S RTO digital oscilloscopes sets an innovation milestone that brings significant advantages for the oscilloscope user in terms of measurement accuracy, acquisition density, and functionality. This application note introduces the working principles of a conventional trigger system and explains the advantages of the real-time capable digital trigger of the RTO oscilloscopes.