This book provides exhaustive knowledge to the students and researchers about the processes with delays and all the possible models for these delayed processes viz. FOPDT, SOPDT and IPDT. It highlights the problem and gives the solution of tuning optimal controllers for these approximated models obtained from model identification techniques. An attempt has been made to provide a number of proven and emerging recent controller tuning formulae for all the models at one place. It further demonstrates some established delay compensation techniques s.a. Smith predictor, to compensate the adverse effects of presence of delay on the performance of the system.