Is airdrop on all iPad platforms?

AirDrop is available for iOS 7 or later - for these these models iPad/iPhone:

• iPhone 5 or newer
• iPod Touch (5th generation) or newer
• iPad (4th generation) or newer
• iPad Air: all models
• iPad Pro: all models
• iPad Mini: all models

Information about using AirDrop, Apple’s short range file transfer protocol, can be found within the iPad User Guide:

Use AirDrop on iPad to send items to nearby devices – Apple Support

Re: “… how does it work …”

If you have other/newer devices, see this article:

How to use AirDrop on your iPhone or iPad - Apple Support

Very old iPad models do not have AirDrop.

If you own a 12 year old iPad 2nd generation running iOS 9, that iPad year and model is far too old.

Sorry.