I started to post this as a comment to Jeremy’s post, but it’s a question I often get from my audience, so I’ll answer it here.

Wil asked, “Can someone please give me a /pointer to a/ primer as to why RSS is such a big deal?”

Others offered some good answers. Here’s mine.

Wil, RSS has different implications for different industries. Yahoo makes money off advertising (among other things), so putting ads in their feeds is a natural.

Other sites make money off usage, so the RSS feed may be more useful as a trigger to drive action. For example, the social networking sites could use RSS to update you when someone posts a relevant comment to a discussion board. (Many use email for this, but that’s becoming less appealing every day what with all the spam/virus filtering. Even in a spam-and-virus-free world, bulk email is a pain in the butt from a production perspective.)

Finally, many sites make money selling products. These kinds of sites are least visited relative to news & usage-oriented sites. You go to Amazon when you want to buy a book, not to get the latest news. E-commerce sites like Amazon could use RSS feeds the same way they use email (without all its attendant headaches) – to update you when a book comes available that you’re waiting for. Software companies could use it to let you know when a new version has shipped or a security hole is fixed.

In many scenarios, RSS is a replacement for bulk email. This has great benefits for both site owners and subscribers/visitors/customers. Yahoo’s adoption of RSS on My Yahoo is a big step in making this an option for the mainstream, not just techies. Once AOL, MSN, Earthlink etc. follow suit – which they will do – it’s only a matter of time before my favorite typical user – my mom – starts subscribing to RSS feeds to do all the things above.