What is the recommended technology or technologies to use in order to make a web page that automatically updates the screen depending on a value change in a database?
For example, there is a web page with a button. When the button is pressed, a corresponding value in a database is changed from off to on. When this is completed, the database is checked again and the button on the web page changes to the corresponding state (either on or off).
Several web pages may be open on different devices and they must also change.