δScuti stars are a group of stars located on or a little above the main sequence of H-R diagram with spectral type from A3 to F5. They are low amplitude single or multi period pulsators with period shorter than 0.3 d. Within the same area there are several groups of variables or special stars correlated  with them, e.g., Dwarf Cepheids,γ Dor variables, Blue Stragglers, Am stars, Ap stars, ROAp variables, λ Boo variables and δ Del variables. In this paper a general review in this field, including the number of  new variables  discovered after 1995, is presented. The most reliable period variation rates for all the high amplitude variables and several low amplitude variables are listed. Statistic shows the higher the rotation rate v sin i is, the lower the light variation amplitude is. Thus within young open clusters high amplitude variables cannot be found. The amplitudes-periods distribution have 3 peaks with the highest of 1.0mag in V at 0.17 d in period. For δ Scuti variables in stellar systems the shorter the average period is, the lower the metallicity and the older the age of the stellar system are.