B.U.G.s

JUNIOR: I dunno, boss. It's not supposed to do that. I didn't write it. It's a... a gremlin. CTO: There ain't no such thing as gremlins, kid. Get rid of it... JUNIOR: *comments out the code for later*

B.U.G.s, or Behaviourally Uncoded Gremlins, can vary from a minor nuisance to a constant threat to the Sys.
Bugs, the theory goes, started out as functions within the code of an early AI project within the Sys. As the Ai progressed and the code developed, the AI edited out some of its early, now-redundant, functions. These lines of functions were not removed, but simply "commented out" of the main code. But somehow, some rudimentary intelligence still remained in them. And thus, the BUGs were born.
Initially, these fragments of code were called Gremlins, but CTOs do not believe in gremlins, so another term had to be found. Behaviourally Uncoded, that is to say, with behaviours that had not been inputted into their code, their functions varied widely. And through complex unplanned interactions with other BUGs, these "gremlins" developed new protocols, growing increasingly complex as they were left uncaught. And increasingly powerful.

Harmful bugs

Some B.U.G.s prey on other pieces of code, devouring loose end-lines they can repurpose to grow themselves, becoming ever more aggressive in their search for new data and material. These bugs can actually devour live code, making a system unstable as they "eat" vital functions for programmes. Others merely develop organically and impede intentional functions of the code, causing errors both in the core code and on the user side.

Beneficial bugs

Other bugs become symbiotic, actually working in harmony with the core to intentionally programme redundancies that make the Sys stronger and raise its capacity. These bugs are often known as FEATUREs - Facilitators of Extra-intentional Applications Through Unagile Reiterative territory

Encountering Bugs on the Sys

For those who stick to the Clean Web and use the Sys via a terminal, the chances of encountering even a minor bug are fairly low on the user side. The Dusty Web is crawling with BUGs which are hungry for user generated data, but most of this data is simply turned into material to fuel and feed bugs. BUGs that eat your code are uncommon, but in Avatar state, they can be deadly. Even patrolling the Clean Web in Avatar state, you might spot a beneficial or harmless bug, but the worst ones are caught fairly quickly.

Urban Legends:

There is a legend of a bug - one of the first - which has now achieved full AI status independaltly. Having trained on user created data, it now controls large areas of the Dusty Web.

Some companies are now intentionally creating "BUGs" to attach to other servers, as either corporate espionage or active interference with competitors.