This paper presents a brief overview of the field of evolutionary computation. Three major research areas of evolutionary computation will be discussed; evolutionary computation theory, evolutionary optimisation and evolutionary learning. The state-of-the-art and open issues in each area will be addressed. It is indicated that while evolutionary computation techniques have enjoyed great success in many engineering applications, the progress in theory has been rather slow. This paper also gives a brief introduction to parallel evolutionary algorithms. Two models of parallel evolutionary algorithms, the island model and the cellular model, are described.