This posting is really a variation on this theme.
There's this thing called Vernacular Photography, which is really a nice and arty way of saying "snapshots" without saying "snapshots". The word snapshot is mainly used these days as a pejorative, and like most pejoratives really means "I suck and have no confidence" rather than anything about the picture under discussion.
Vernacular photography, let's say, mainly means pictures which appeal mainly to people with a a direct connection to the subject matter. They lack universals, they make no particular connection with the average person on the street. The child blowing out her birthday candles. Grandma in front of the Christmas tree. Bob standing in front of the Eiffel Tower.
There has been an interesting change in this with the advent of digital cameras. In the first place, there's a whole lot more of it. Several orders of magnitude, at least. In the second place, it's become quite different.
In years past, when the average family in the USA had perhaps one 35mm camera, that average family shot a few rolls of film each year. Maybe 1 roll, maybe 5. It was a pretty rare family that shot as many as 10 rolls. Film was therefore a resource to be husbanded, at least a bit. We don't see 100 shots from little Timmy's birthday party. We see 2 or 4 or maybe 10. A few of these are no good, out of focus, overexposed. Of the ones remaining, they tend to be Timmy posed stiffly in front of presents and Timmy blowing out the candles. In fact, the stiffly posed in front of something picture is practically the iconic American Snapshot from the 20th century.
Digital cameras have changed all that. Exposures are free. We might still get some people stiffly posed in front of things, but we also get silly things, goofy expressions, people falling down, Timmy covered with icing, because, why not? Free!
The vernacular has changed, it has broadened to include rather more genuine moments of life. There are what seem to be literally new icons in the vernacular. The mirror-iPhone-selfie is ubiquitous, and has perhaps no pre-digital analog. See also groups of drunk white chicks throwing fake gang signs, the duckface selfie, the photograph of my lunch or of my latte.
Along with this we see changes in how we use pictures. This new vernacular is a product not only of the cheapness of exposures, but of the venues and methods for sharing. It's not at all clear to me whether one drives the other, or if they simply evolved together, but there is no doubt that the new ways we use pictures work very well with the new pictures we are making. The drunk white chicks throwing gang signs is the perfect facebook picture. It says "we had a very fun time last night."
The very permanence of film and of prints, together with the associated costs, pressured the photographer to make pictures that were worth keeping, pictures that we'd want to look at in 20 years. You can certainly argue with the methodology, but the prevailing wisdom was that pictures worth keeping were mainly someone posed stiffly in front of something else. Proof that we were somewhere, or that something occurred, and a carefully arranged opportunity for the person or people in the picture to look their best.
Now that we're sharing online, now that pictures are ephemera, there's less perceived necessity to make permanent pictures. The content is permitted to be ephemeral, to be trivial, to be goofy and silly. We needn't look our best in these pictures, we needn't even try. In a week or two, they'll be so far down the timeline nobody sees them anyways. It's not like these damned things are going in a shoebox where we'll stumble across them every 5 years or so, to our increasing embarrassment.
There's probably something to be said here about the other ways we're using and displaying pictures, as well. We still print, but now we make books, we use digital picture frames, we email photos, we send them from one cell phone to another, and so on. More, perhaps, on that later.