Under the title of Function Algebras we may now include a very large number of works. published mainly in the last decade, which consti tute one of the important chapters of functional analysis. This chapter has grown up from various problems. permanently furnished to mathe matics. by the theory of functions. using modern methods of algebra, topology and functional analysis and presenting large possibilities of applications in operators theory. Herefrom proceeds its living character, the variety of obtained results. the variety of forms and contexts in which these results can be found. This also explains the difficulty of an exhaustive exposition of these problems. The purpose of the monograph is to present a coherent exposition of the fundamental results of this theory with an orientation to their applicability to the theory of operator representations of function alge bras. The idea of such a work appeared during the seminaries on function algebras held at the Mathematical Institute in Bucharest. under the direc tion of C. Foia~ and at the Faculty of Mathematics and Mechanics under the direction of N. Boboc. It is a pleasure for the author to express his gratitude to C. Foia~ for assistance in his efforts. in general. and for the large contribution the discussions and cooperation with him had brought in the elaboration of this monograph. I also would like to thank N. Boboc for the clear discussions we have had during the seminaries and the elaboration of some chapters.