A survey devoted to A(0)-condensate in gauge theories at high temperat
ure is presented. Both theoretical foundations of the spontaneously ge
nerated condensate and known methods of its calculation are discussed.
As the most important consequence, the SU(N) global symmetry breakdow
n is investigated in detail. The influence of A(0) on matter fields is
studied in different aspects. Some new results concerning this subjec
t are reported as well.