Harmonic mixing is a DJ technique that involves selecting and blending tracks whose musical keys harmonize, enhancing the overall sonic cohesion of a mix. By aligning the key signatures of songs, harmonic mixing creates smoother transitions between tracks, avoiding dissonance and enhancing the musical flow. DJs often use software or tools to analyze the key of each song, allowing them to seamlessly mix tunes that share compatible harmonic elements. This technique is not only essential for maintaining a consistent and pleasing auditory experience but also contributes to the overall emotional impact of a DJ set, fostering a more engaging and enjoyable connection with the audience.