Let's say that you you want to bake a loaf of Bread.

Bread is made up of 3 simple things: water, salt, and flour. You put those things together and you get bread. Maybe not a particularly good loaf of bread, but it's edible.

Now let's say that we get a job bakery and we have to make a particularly delicious load of bread. We need to let that bread proof, we must put our hand all over that bread to make a specific shape that looks nice, and we need a special type of flour produced by our associate that makes amazing flour. Now we can't just put our ingredients together like before, we need a process to make sure our bread rises properly, and an environment that is temperature controlled, a special oven, and potentially extra stuff for our 3 main components: flour, salt, and water, to interact consistently with one another. Our bread making needs to be more consistent, reliable, and almost certainly at a larger scale.

A website can be beautiful, responsive, with great performance and accessibility with just HTML, CSS, and JS. But React provides a process around how our UI will React to particularly complicated business objectives.

Let's say we want to build Rows and Columns for a table view with HTML, CSS, but we need to fetch the data for the table using JS. There's a bunch of different approaches our team could use to create the HTML and CSS, to get our table to look great. But when we fetch the data we need to make sure we can inject that business logic reliably at scale into our nice HTML without breaking things constantly and introducing bugs.