NetNavi: Stands for Network Navigator. These Navis are stored in PETs and have special abilities and attacks. Male Navis typically have their name end in Man (MegaMan, GutsMan, IceMan, BubbleMan, etc.) while the female Navis don't (Roll, Ring, etc.). All Navis have a symbol which is typically on their chest and maybe their shoulders. Navis can Log Out of a system (retreat back to their PET or an access point they used to get there) or be Deleted (though the deleted data will reform somewhere but can take varying amounts of time depending on how badly the Navi was injured prior and during the deletion)

PET: Stands for PErsonal Terminal. These devices come in several models and house the Navis. These devices are the only way to get Battlechips (or Battlechip data for those who use a Progress PET or a Link PET) to the Navis. All models, excluding the Plug-In PET and the Link PET connect to the network via infrared connection, while the other two use Jacks to access the network (hence the term, "Jack in, *Insert Navi name here*! Power up!" that a lot of characters shouted when their Navis were accessing the network).

NetOp: Stands for Network Operator. These are humans with PETs and Navis.

Battlechip: Little chips used to modify a Navi with attacks (Or a totally new form in MegaMan's case with his Double Soul ability). They come in a wide variety, ranging from blaster weapons to swords to minor teleportation to even explosives. These chips all have a cooldown period, meaning that once one has been used that it can't be used again for a while. The only exclusion to this is the Synchro Chip.

Synchro Chip: Only able to be used with Advanced, Advanced II, Progress, and Link PETs. These little chips usually have what looks like a small green dome in the center (unless it's a corrupted one, known as a Dark Synchro Chip which then has a purplish middle). They are the only thing that can enable Cross Fusion.

Cross Fusion: The fusion of a NetOp and a NetNavi in the real world. The only place this can be used is in a Dimensional Area. The only exceptions to this are the Rush Synchro Chip and if the real world merges with the Cyber World. The Rush Synchro Chip can only be used by one who manages to convince Rush to phase from the Cyber World to the Real World and merge with the Synchro Chip around his neck. There is also a Reverse Synchro Chip that merges NetOp with NetNavi into the Cyber World but is very risky as they have yet to be finished developing.

Dimensional Area: Typically generated by a probe that is launched at a target, typically a building. These can't be accessed from the outside except if someone is going really fast and initiates Cross Fusion as soon as they hit the edge of the Dimensional Area (which is easy to spot since it is typically orange and purple.) Dimensional Areas allow Rouge Navis from the Cyber World to cross over to the Real World as well as allow Viruses to come with them. The only way to remove a Dimensional Area is to either destroy the generator that made it, defeat the Navi that came with it, or force the Navi to retreat back to the Cyber World.

Dark Chips: These are very powerful, but at a steep price. They are very addicting, not only to Navis but NetOps as well (as long as they're a Dark Synchro Chip). They also slowly destroy the Navi and/or NetOp using them as well as corrupting them to make them Rouge Navis that are evil. There are slight chances that a Navi and/or NetOp can fully recover with little to none side effects but they are hard to pull off.

Viruses: Like everything else in the Cyber World, these guys have a physical manifestation (i.e. there's a virus that looks like a tiny miner). All Viruses are typically weak and can be taken out easily.

Program Advanced: A very powerful combination involving three Battlechips. There are many Program Advanced and each one is difficult to master.

Cyber World: Where Navis can go to hang out, battle, and/or cause mischief. This world heavily mimics the Real World in the sense that the data for a building usually looks like the building. For example, the data for a bank will form together and look similar to the bank in the Real World, though their functions are different (Real World Bank is for money while the Cyber World one would be a data bank).