1. Why plasma harmonics? -- 2. Theoretical basics of plasma harmonics -- 3. Low-order harmonic generation in plasma plumes using nanosecond and picosecond driving pulses -- 4. High-order harmonic generation in plasma plumes using picosecond pulses -- 5. Plasma HHG using femtosecond pulses -- 6. Characterization of plasma harmonics -- 7. Recent achievements in plasma harmonics.