The history of electronics is really a vast area and it is not possible to present the whole details of the systematic history in this limited scope. Anyway electronics which started as philosophy then physics then electrical engineering has now got its own identity and going to be even more diverse in the future. There is no doubt that the modern electronics as we see it today started from the birth of the vacuum diode of Sir Ambrose Fleming. On the centenary year we should remember that great man and both his predecessors and successors. The changes of 20th century are mainly due to electronics, there no doubt about it. All the systems today are almost electronic.