Check out example codes for "install bootstrap angular 9". It will help you in understanding the concepts better.

Code Example 1

npm install bootstrap --save

Code Example 2

From angular cli:

npm install --save bootstrap
npm install --save jquery

Then add the following paths to angular.json:

"node_modules/bootstrap/dist/css/bootstrap.css" in the projects -> architect -> build -> styles array
"node_modules/jquery/dist/jquery.js" in the projects -> architect -> build -> scripts array
"node_modules/bootstrap/dist/js/bootstrap.js" in the projects -> architect -> build -> scripts array

Code Example 3

@import "~bootstrap/dist/css/bootstrap.css";

Code Example 4

$ npm install --save bootstrap

Code Example 5

....      "styles": [        "node_modules/bootstrap/dist/css/bootstrap.min.css",        "src/styles.css"      ],      "scripts": [          "node_modules/jquery/dist/jquery.min.js",          "node_modules/bootstrap/dist/js/bootstrap.min.js"      ].....

Code Example 6

ng add @ng-bootstrap/ng-bootstrap

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