I have a question for you today and it's a general purpose one. I want to learn more about the modern web development. I've watched many tutorials and courses online but as I search more and more, I get confused even more.
I will describe my main question through an example. I want to create a web application which displays data retrieved from a DB, which is populated with some sensor values.
I've seen many online lessons creating this kind of an app using React.js and other using Express.js or pure Node.js. I understand that the React is for the frontend and the Express is for the backend. However similar things can be made using both frameworks.
Using the Express.js I can create a server side application which handles the the requests to the DB's API, handles the routing between pages and can handle HTTP requests and generate EJS templates to show the data to the screen. My question is where does React come and help to the production of the app, especially when the rendering is done from the client and not on the server (which makes things worse for SEO).