What's shown
The image is drawn in a monochrome outline style showing a bald man with bare shoulders and neck. He presses both palms to his cheeks, his eyes are half-closed, his lips form a pleased half-smile, and his head is tilted slightly back. The pose resembles a moment of bliss after washing one's face or applying cream, and it's exactly this everyday association that forms the basis of the meme: the character looks as if he's just started feeling truly good.
The lines are extremely simple: a few strokes mark the eyebrows, eyelids, nose, and mouth, with no shading or color. Thanks to that, the figure is easy to recognize even at a small size and lends itself well to reworking. The character has no individual features, so it can be inserted into any context without tying the image to a specific person.
Origin
The source material was a stock photo of a man washing his face. Such shots were often used in skincare advertising and beauty blogs. The outline version that became popular online was created based on that photo, but exactly who drew it and when hasn't been determined: the authorship remains unknown.
It's presumed that the drawing appeared on 4chan's /b/ board in 2011, and the meme's official record in specialized archives is dated June 13, 2011. It's important not to confuse it with "Feels Good, Man" or with the Wojak character (Feels Guy), whose names are similar. A connection to Rage Comics or to Trollface isn't confirmed in sources, so classifying the meme as part of the rage comics genre is tentative.
How the meme spread
In August 2012 a series appeared on 4chan's /sp/ board in which the face of the "That Feel" character was overlaid on the template, placing the picture in the context of the recognizable emotion "this is that very feeling." This trick showed that the template suited new faces and captions well, and from that point the number of reworkings began to grow.
In December 2012 a NeoGAF forum member posted a version with a stock photo of Tom Cruise, and in April 2013 a thread appeared on Facepunch with water-themed edits, where one participant replied with the original stock shot. By around mid-2013 the template had appeared on the /vg/ board in versions themed around The Legend of Zelda and Planetside 2. The meme quickly moved from one community to another while keeping its recognizable outline.
Typical use
Most often Feels Good is a reply to someone else's post. Someone wrote a good joke, suggested a good option, or shared pleasant news, and in response people post the picture of the blissful face. A caption usually isn't needed, and if there is one it's short: an exclamation or a quote from the discussion explaining exactly what the responder is pleased about.
Sometimes the meme is used ironically. Someone brags about a success, and the reply in the form of the smug character expresses approval with a hint of mockery. There are also variations where only the object changes: instead of holding their own face, the hands hold a mug of tea, a slice of pizza, or a game controller, while the pose and expression stay the same.
Why the meme works
The humor rests on the contrast between a mundane action and a disproportionately strong reaction. Washing one's face is a routine almost nobody notices, but the character experiences it as a moment of supreme bliss. That gap makes the picture funny and suitable for almost any occasion, from trivial matters to notable events that bring joy.
Minimalism and an expressive pose let the emotion register instantly, even in a small image or thumbnail. The character needs no explanation, so the meme carries over between platforms without losing its meaning. It's exactly this simplicity — one frame, one clear feeling — that explains why Feels Good remains a prominent reaction image.