local storage

function createItem() {
	localStorage.setItem('nameOfItem', 'value'); 
} 
createItem() // Creates a item named 'nameOfItem' and stores a value of 'value'

function getValue() {
	return localStorage.getItem('nameOfItem');  
} // Gets the value of 'nameOfItem' and returns it
console.log(getValue()); //'value';localStorage.setItem('myCat', 'Tom');

var cat = localStorage.getItem('myCat');

localStorage.removeItem('myCat');

// Clear all items
localStorage.clear();
function setItem(name, value) {
  localStorage.setItem(name, value);
}
function getItem(name) {
  localStorage.getItem(name);
}
function deletItem(name) {
  localStorage.removeItem(name);
}
function clearStorage() {
  localStorage.clear();
}localStorage.setItem('user_name', 'Rohit'); //store a key/value
var retrievedUsername = localStorage.getItem('user_name'); //retrieve the key// Set
localStorage.setItem('monChat', 'Tom');

// Get
localStorage.getItem('myCat');

// Remove
localStorage.removeItem('myCat');As the answers here already talk about the coding aspect. I will talk about
the concept.
Local storage is basically an object stored in the specific browser you are 
using in that moment. And thus it is tied to that browser in that device. It's 
duration is infinite so it never expires

If you only want to store data that only lasts for that browser session(
starts when you open a window and ends when you close it) then the best choice
is sessionStorage