componenet- includes all files its is the part of the app html+css+js
single page application - react
react rins code from app
all html code written will go to index.html
to create componenr-put a file and name it js
state is a object which updates view it is unchangeable it act as medaiator bw js and html
bootstrap is a library to create buttons things lik ethat
bootstrap css link paste in head tag in index.html