What are Core Web Vitals and how do you improve them?

Related HTML & CSS interview questions

• How does the browser render a web page?

  The browser parses HTML into a DOM and CSS into a CSSOM, combines them into a render tree, computes layout (reflow), paints pixels and composites layers onto the screen.

• What is the difference between async and defer on script tags?

  Both download the script without blocking HTML parsing. defer waits until parsing finishes and runs scripts in document order; async runs a script as soon as it is downloaded, which can be before or after parsing and in any order.

• What is the difference between cookies, localStorage and sessionStorage?

  Cookies are sent to the server with every matching request and can expire; localStorage persists until cleared and stays in the browser; sessionStorage lasts for the current tab only.

• What is the difference between em, rem, %, vh and vw in CSS?

  em is relative to the parent font size, rem is relative to the root font size, % is relative to the parent’s relevant size, and vh/vw are 1% of the viewport height or width.