Due to the rapid development in technology, needs of mankind for fast speed is growing. Bio computers use systems based on biologically derived molecules i.e. DNA and Protein. The term bio computing was initiated by Dr. Adleman through his article on solving HDPP using DNA and later he performed an experiment for this technology. Bio computers have been developed on the basis of new technology known as nanobiotechnology. It is a combination of two technologies, nano scale materials and biologically based materials. These computers use living cells for the purpose of storing information and to perform complex calculations. The storage capacity of bio computers is totally superb. Just one gram of DNA can hold information equal to one trillion compact discs. These DNA computers are small, fast and highly efficient systems having various properties. These bio computers are extra ordinary energy efficient. These have the capability to run 2 x 1019 operations per joule.