What do you understand by "Web Workers"?
Now assume any webpage which requires some calculation intense logic on webpage when any button is clicked. If the button is clicked the script starts executing and all other controls on webpage is blocked until the script completes execution. To overcome such situation HTML5 introduced Web Workers.
A worker is an object created using a constructor
Workers run in another global context that is different from the current window which makes possible to run scripts concurrently on webpage.