The article reviews the development and applications of mid-infrared frequency combs, which are coherent light sources emitting a broad spectrum of discrete, evenly spaced narrow lines with absolute frequencies measurable within atomic clock accuracy. The mid-infrared spectral region (2-20 μm, 500-5,000 cm⁻¹) is of significant interest due to its strong molecular fingerprints, making it ideal for precision spectroscopy and non-intrusive diagnostics. The introduction of laser frequency combs in the late 1990s revolutionized frequency metrology and has led to numerous advancements in fields such as astronomy and attosecond science. The extension of frequency comb techniques to the mid-infrared spectral region is currently under exploration, with novel approaches based on laser gain media, nonlinear frequency conversion, and microresonators promising to expand the applications of frequency combs. The article discusses various methods for generating mid-infrared frequency combs, including mode-locked lasers, difference frequency generation, optical parametric oscillators, and Kerr comb generation. Each method has its advantages and challenges, but recent progress has led to the development of efficient mid-infrared frequency comb generators with wide spectral coverage and high power per mode. The applications of mid-infrared frequency combs are primarily focused on precision spectroscopy of molecules, where they enable rapid and sensitive acquisition of molecular spectra over a broad spectral span. Frequency combs are used as frequency rulers to measure the absolute frequency of atomic or molecular transitions, providing better understanding of energy levels and enabling new tests of fundamental physical laws. Direct frequency comb spectroscopy, particularly dual-comb spectroscopy, offers significant advantages in terms of measurement time and resolution, making it a promising technique for future applications. The article concludes by highlighting the potential of mid-infrared frequency combs in various fields, including astronomical spectroscopy, trace gas detection, and ultrafast phenomena. It emphasizes the need for further technological advancements to fully realize the potential of mid-infrared frequency combs, such as direct laser emission of few-cycle phase-coherent pulses and improved materials for efficient nonlinear frequency conversion.The article reviews the development and applications of mid-infrared frequency combs, which are coherent light sources emitting a broad spectrum of discrete, evenly spaced narrow lines with absolute frequencies measurable within atomic clock accuracy. The mid-infrared spectral region (2-20 μm, 500-5,000 cm⁻¹) is of significant interest due to its strong molecular fingerprints, making it ideal for precision spectroscopy and non-intrusive diagnostics. The introduction of laser frequency combs in the late 1990s revolutionized frequency metrology and has led to numerous advancements in fields such as astronomy and attosecond science. The extension of frequency comb techniques to the mid-infrared spectral region is currently under exploration, with novel approaches based on laser gain media, nonlinear frequency conversion, and microresonators promising to expand the applications of frequency combs. The article discusses various methods for generating mid-infrared frequency combs, including mode-locked lasers, difference frequency generation, optical parametric oscillators, and Kerr comb generation. Each method has its advantages and challenges, but recent progress has led to the development of efficient mid-infrared frequency comb generators with wide spectral coverage and high power per mode. The applications of mid-infrared frequency combs are primarily focused on precision spectroscopy of molecules, where they enable rapid and sensitive acquisition of molecular spectra over a broad spectral span. Frequency combs are used as frequency rulers to measure the absolute frequency of atomic or molecular transitions, providing better understanding of energy levels and enabling new tests of fundamental physical laws. Direct frequency comb spectroscopy, particularly dual-comb spectroscopy, offers significant advantages in terms of measurement time and resolution, making it a promising technique for future applications. The article concludes by highlighting the potential of mid-infrared frequency combs in various fields, including astronomical spectroscopy, trace gas detection, and ultrafast phenomena. It emphasizes the need for further technological advancements to fully realize the potential of mid-infrared frequency combs, such as direct laser emission of few-cycle phase-coherent pulses and improved materials for efficient nonlinear frequency conversion.