Significance In 2023, Pierre Agostini, Ference Krausz and Anne L Huillier had been awarded the Nobel Prize in Physics for their contribution in experimental methods of generating attosecond pulses of light for the study of electron dynamics in matter. Based on their pioneering work of high harmonics generation (HHG), generation and characterization of attosecond pulse trains (APTs) and isolated attosecond pulses (IAPs), a whole new physics research field named attosecond science was opened up. With the rapid development of attosecond science in the past two decades, extremely short IAPs have been generated and applied in photon spectroscopy and attosecond transient absorption spectroscopy (ATAS), providing researchers more powerful tool to study the ultrafast electron dynamics in atoms, molecules and condensed matter than ever with attosecond temporal resolution. These ultrafast processes include the photoionization time delay in atoms, ionization difference of polar and nonpolar molecules, electrons migration in multiatomic molecules, measurement of Auger decay process, innershell transition and probing of multielectron dynamics.Progress Thanks to the progress of the ultrafast laser techniques as pumping lasers, multiple methods for gating, and fine spectral chirp for compensation in the past two decades, the spectrum of the IAP has expanded from tens of electron volts to hundreds of electron volts and its pulse duration record is getting compressed. Although many research groups have succeeded in achievement of