Apple S iPhones through the years

LOS ANGELES - This year it’s all about the S.

Apple introduces a new iPhone every year--but redesigns the iconic device every two years.

So while 2014 gave us the larger, more stylish iPhone 6 and 6 Plus--Apple’s best-selling iPhones ever--expect a new model this year that will look the same, “but have one major, new feature,” says Mark Gurman, a senior editor with the 9to5Mac blog.

Let’s go back in time for a minute and take a good look at those "S" features.

--We all love to take videos for our Facebook and Instagram feeds on our smart phones, but it wasn’t until 2009 that video from smartphones became mass market. That’s when Apple added video features to the first “S” edition iPhone, the 3GS.

--Siri, when did we first meet? That would have been 2011, when the personal digital assistant was first introduced for the iPhone 4S. And we’re still talking about her today. Siri is expected to be touted in a big way at the upcoming Apple event in San Francisco Wednesday, when Apple debuts the new iPhone's, expected to be named the 6S and 6S Plus. Siri is seen morphing beyond the iPhone to also be featured on Apple’s streaming box, Apple TV, as well.

--It was in 2013 when Apple brought us Touch ID, the ability to open our iPhones with the fingerprint sensor.

And speaking of fingerprints, the biggest feature for the new iPhones is expected to involve our fingers as well.

It’s called Force Touch, which was first introduced on the Apple Watch in March.

It’s a shortcut that “will enable people to get tasks done even quicker,” says Gurman. Hold your fingers down on the screen a little longer, and “the phone will know,” to move things faster. It’s a feature that’s “oriented to saving time,” he says.

The new iPhones are expected in stores by the end of the month.

Follow Jefferson Graham on Twitter and listen to his daily audio #talkingtech reports on Stitcher and TuneIn.