How to use libraries installed via NPM in a project?

Question

npm

I understand that this question has been raised many times, but I have not found an intelligible answer to it. Suppose I decide to install some library or framework, let's take the same Bootstrap. With Node.js installed, I ran the command in the console npm i bootstrap -D. The necessary files were written somewhere in the bowels of the node_modules folder. How can I now use them in the project, how to connect them to the html page, without manually prescribing everything in the path?
PS I use Gulp as a builder. I heard about some miracle bunch of gulp + browserify, but in practice I did not use it.

Answer 1

1. Bootstrap is not a dev dependency (-D) because it is used after the project is built, not during development