Since its founding nine years ago, Reddit has stuck to its own weird guns.

The site, where users find, share and talk about web links and photos, has been faithful to an antiquated design and still looks like an online message board plucked from the 1990s — think Craigslist, but with more Lolcats. You don’t need to hand over any personal data, not even an email address, to sign up and post or view an item. Discussions are often peppered with vulgar schoolyard humor.

And unlike many other Internet start-ups, Reddit has never fully embraced the dominant business model of selling advertising to support its free service.

But that is about to change.

The company is trying to jump-start its advertising business, as well as bolster some smaller moneymaking efforts. Its challenge is to figure out how to become a real business without changing the essential nature of the service and alienating its powerhouse constituency of 114 million intensely loyal monthly users.

If it fails, those users could revolt and ultimately depart en masse, turning Reddit into an also-ran like Myspace — another social web giant that faded into obscurity.