Pulsed field gel electrophoresis is a technique used for the separation of large DNA molecules by applying to a gel matrix an electric field that periodically changes direction. Pulsed-field gel electrophoresis (PFGE) is a method used to separate large segments of DNA using an alternating and cross field. In a uniform magnetic field, components larger than 50kb move through the gel in a zigzag pattern, allowing for more effective separation of DNA molecules. This method is commonly used in microbiology for typing bacteria and is a valuable tool for epidemiological studies and gene mapping in microbes and mammalian cells. It also played a role in the development of large-insert cloning systems such as bacterial and yeast artificial chromosomes. PFGE can be used to determine the genetic similarity between bacteria, as close and similar species will have similar profiles while dissimilar ones will have different profiles. This feature is useful in identifying the prevalent agent of a disease. Additionally, it can be used to monitor and evaluate micro-organisms in clinical samples, soil and water. It is also considered a reliable and standard method in vaccine preparation. In recent years, PFGE has been widely used as a powerful tool for controlling, preventing and monitoring diseases in different populations Discovery The discovery of PFGE can be traced back to the late 1970s and early 1980s.One of the earliest references to the use of PFGE for DNA analysis is a 1977 paper by Dr. David Burke and colleagues at the University of Colorado, where they described a method of separating DNA molecules based on their size using conventional gel electrophoresis. The first reference to the use of the term "pulsed-field gel electrophoresis" appears in a 1983 paper by Dr. Richard L. Sweeley and colleagues at the DuPont Company, where they described a method of separating large DNA molecules (over 50 kb) by applying a series of alternating electric fields to a gel matrix. In the following years, several groups of scientists improved and fine-tuned the technique, including Dr. J. Peter Gerhardt and colleagues at the University of Alabama in Birmingham in 1984, and Dr. Mark Scherer and colleagues at the University of Minnesota in 1986. By the late 1980s and early 1990s, PFGE had become a widely used technique for the separation and analysis of large DNA molecules in various fields of research, including molecular biology, genetics, and biotechnology. PFGE Types There are various