A synchrophasor is a device used in electrical engineering to measure the electrical waves on an electricity grid in real-time. It captures data on voltage and current at precise intervals, allowing for a detailed analysis of the grid's performance. This information helps operators monitor the stability and reliability of the power system. By using phasor measurement units (PMUs), synchrophasors can synchronize data from multiple locations across the grid. This synchronization is crucial for detecting issues like overloads or faults, enabling quicker responses to maintain the balance between supply and demand in the electrical network.