String Theory : In layman's terms.

It has been an age old quest to understand, of what stuff we and all the object we see around are made. Earlier in the times of Greek philosophers like Aristotle, it was thought that we all are made up of five fundamental elements,  and they even tried to understand the structure of those elements.You will we amazed to know that the geometry that we study in school which defines line , points, circle, polygon etc was actually invented by Euclid to arrive at the structure of those elements.Hence, it was his book 'Elements' from where geometry started.And in the final chapter he was able to arrive at a complex geometry involved in the structure of those elements.However, later it was understood that those were not fundamental constituent of matter, but still we kept the word element. As our know how progressed we were able to conclude that things are made of elements and these elements have more fundamental constituent called atom , which once was also thought to be indivisible. Now, as science
advanced and our know how enriched we were ab le to understand that these atoms were made of sub atomic particles and again these sub atomic particles were made of more fundamental stuffs.So, what is the fundamental constituent of a matter has been a function of our scientific advancement,  limited by our scientific know how. So, there must be something fundamental,which we yet not able to find.

This quest for the fundamental constituent of nature led theoretical physicist to string theory.As we continue to break a matter, we will arrive at more fundamental thing.At the end of it we are obviously not going to arrive at matter ,logically it was deduced,. In the end we will have a vibrating string.This string must not be confused with actual string which is a matter.It will we a closed vibration or disturbance in the form of small strings.For better understandinग you can imagine a pulse of contraction and rarefaction created in air when you speak .It's just a disturbance of air particles travelling.Similarly string too would be a disturbance in space but an electromagnetic one which has shape of string as it travels. Now as this string vibrates with different matter and which add up to different matter leading to infinite combinations.so what is fundamental is the frequency with which this string vibrates. It is not very difficult to appreciate same thing in real life.Do you know when you touch your table what you experience is millions of electron level particles hitting your hand and u visualize it as something solid and we say it is a object.when u heat the stuff , these particles vibrate faster and it heats your hand with more energy and u say it is hot.Thus, vibrations are at macro level being perceived as solid matter.similarly in case of vibrating strings at multi level high we perceive it as apple but at fundamental level it is composed of tiny vibrating strands of energy called strings
This is what we call string theory