The definition transitioned from "viral internet jokes" to "image intended to be funny". Some memes are just edited screenshots of Twitter posts or other viral images. "Text intended to be funny" is a subset of memes referred to as "greentext"; due to 4chan quotes being used for storytelling and the text being green.
The transition period went from Image macro --> Demotivational Posters --> Trollface/Rage Comics --> 4 panel comics --> Memes. This took place over the time period of 2004-2009 and really took off with sharing images over Twitter as the ability to get a viral image became easier.
Now's my chance to ask a professional: when did memes become "dank"? Mid-2012?
The dankest they ever were was in October and November of 2016 - they've become less dank over time but the economists over in /r/memeeconomy keep their eyes out on /r/dankmemes for the latest and dankest memes to add to their portfolios.
It's a thriving industry with lots of karma to be had - it takes experts to identify a dank meme before it is ripe.
[1] https://trends.google.com/trends/explore?date=all&geo=US&q=%...
Image Macro != Meme
"The term "image macro" was first coined in Something Awful[2] in 2004. In the forums, users could summon a number of default image macros using simple commands like [img – macro], for example, timelines, "Aces!" and "Captain Obvious to the Rescue!" images. The name is derived from the computer scientific definition of a macro: a rule or pattern that specifies how a certain input sequence should be mapped to an output sequence according to a defined procedure. The earliest definition of an image macro was submitted by SomethingAwful forum user Eclipse[3] on February 12th, 2004."
Hell, you could consider print advertising to be a form of image "macros". We need a better name that is descriptive or at least doesn't sound so abstract and far removed from the virality/humor aspect.
Even if that's a sufficient and satisfactory explanation, it doesn't address either the claim of TFA, or parent's question.
What app do you use to traverse socially ... ?
Text overlaid on an image is not inherently a meme - even if the bot that made it shares it on instagram.
Memes have always been short and simple