cdnjs is a free distributed JS library delivery service.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
JSDelivr is a free public CDN for open-source projects. It can serve web files directly from the npm registry and GitHub repositories without any configuration.
Next.js is a React framework for developing single page Javascript applications.
Vercel is a cloud platform for static frontends and serverless functions.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.