Signal And Noise (A.K.A. "Human Souls ARG" or "Conscious Human Souls") is an ARG.

Important video

Important video.

It started on February 12th with a mysterious advertisement on MS Paint Adventures that contained an encrypted link to a YouTube video called "zero", which contained links to more YouTube videos. There were also imgur links to nonograms, and links to pastebin and mediafire.

Messages are often cryptic and coded, and appear in no obvious chronological order (although the Tumblr and Twitter seem to be in real time, and serve as a prequel of sorts to the Youtube channel itself.) Most updates now appear via the Pangent Tumblr.

New players can get help catching up by using the chatroom at Chatango. Previously there was a chatroom at Chatzy.

There are two Tumblrs dedicated to solving the ARG, where you can find solutions and submit your own. Currently solves are posted at HumanSoulsArg. There was also conscioushumansouls, which is less active at the moment.

The story revolves around a few characters who work for or are related to a technology company named Pangent Technologies, and the Cube/555, an object of questionable origin that seems to act as a way to store human minds. There is a Youtube channel which includes coded and cryptic messages from a Man (believed to be Eric/CHS) and a Woman (codenamed Argentina). Most of the videos are unlisted and only found through clues in other videos. There is also a Tumblr, apparently run by Argentina before she was uploaded.

"We are the same as we ever were. We are people. We are conscious human souls. We are the signal that rises above the noise." — Eric
The original six videos on the channel tell one story:

Two minds were uploaded into a computer just before their deaths: a man (Eric) and a woman. Eric seems to have been in the computer for a while, though the woman, having recently passed, is only just discovering what it means to be uploaded. And Eric may not be lying to her, but he's also not telling her the whole truth.

The limitations of the system mean that both of them are incomplete and missing data - shadows of their former selves. She is still mourning the loss of her husband Bill, who was killed in an accident. Eric, meanwhile, has apparently lost his wife (Charlotte) and his daughter.

"My life has the deepest lore. You don’t even know." - PT Tumblr
The storyline is affected by user input and theories. Players have been asked to input data in real time to the Pangent Technologies Twitter, or more recently to the Tumblr.

The Pangent Tumblr has mostly been a personal blog for Argentina, while she was working at Pangent Technologies in London on Project 555, aka the Cube. This has been affected by player input and takes place before the Cube videos. The Cube is said to have unusual properties when it comes to time, suggesting that events in both time zones can still be changed and affected by players. It has also been suggested that the Pangent Tumblr is actually a reconstruction of lost data, a project by Eric in the Cube.

Make sure to read the Pangent Memes page ;)

For history, see The Trailhead.