The basic ideas on the nature of young T Tauri stars (TTS) are briefly out lined and some examples of spectral investigations of the stars are considered. Photometric and spectral variability of TTS is caused by circumstellar extinction, magnetic activity, and accretion of matter from the circumstellar disc onto the stellar surface. In 1990s, series of high resolution spectra of several TTS were obtained with the SOFIN echelle spectrograph installed at the Nordic Optical Telescope. In particular, rotational modulation of emission lines with a period of about 2.7 days was revealed in spectra of RW Aur A. This was interpreted in terms of magnetospheric accretion model with inclined magnetic rotator. Spectra of TTS obtained with the UVES spectrograph at VLT revealed that the effect of veiling, usually attributed to accretion, is caused largely by chromospheric emisions. It is suggested that the accretion is an additional source of heating in chromospheres of TTS.