Are airdrops free money?

Could you possibly elaborate on the concept of "airdrops" in the realm of cryptocurrency? Are they indeed considered as a form of gratis financial gain, or is there a deeper, more nuanced understanding to this term? I'm curious to know if airdrops are merely a marketing ploy or if they serve a legitimate purpose within the crypto ecosystem. Furthermore, are there any caveats or conditions attached to these airdrops that one should be aware of? Your insights would be greatly appreciated.