jQuery is a fast, small, and feature-rich JavaScript library used to simplify JavaScript programming.
John Resig developed jQuery in 2006.
The `$` symbol is a shorthand alias for jQuery in code.
`$('#demo')` is the correct syntax to select an element with id 'demo' in jQuery.
`$(document).ready()` runs the code after the DOM is fully loaded.
jQuery does not handle databases; it is used for client-side scripting like DOM manipulation and AJAX.
CDN stands for Content Delivery Network, used to serve libraries like jQuery faster from external servers.
`hide()` is a jQuery method to hide selected HTML elements.
`jQuery.noConflict()` allows jQuery to work alongside other JavaScript libraries without conflicts.
Google, Microsoft, and the official jQuery website provide CDN services for jQuery.