Recent progress in precision control of pulse repetition rate and carrier-envelope phase of ultrafast lasers has established a strong connection between optical frequency metrology and ultrafast science. A wide range of applications has ensued, including measurement of absolute optical frequencies, precision laser spectroscopy, optical atomic clocks, and optical frequency synthesis in the frequency- domain, along with pulse timing stabilization, coherent synthesis of optical pulses, and phase-sensitive extreme nonlinear optics in the time-domain. In this contributiori we discuss the impact of the femtosecond optical frequency comb to molecular spectroscopy. Measurements performed in the frequency-domain provide a global picture of molecular structure at high precision while providing radio frequency clock signals derived from molecular optical standards. Time-domain analysis and experiments give us new possibilities for nonlinear optical spectroscopy and sensitive detections with real-time information.