The Infected

The infected are one big group all survivors deal with on daily basis.

The infected come in varied sizes, shapes and levels of consumption. They often move clumsily, twitching or dragging their limbs oddly like they wouldn't really know where they are. Some have wounds or broken limbs but such petty things don't seem to bother them at all. The few agile ones usually also seem the most human looking. Some of the infected aren't even that dirty but they all ooze the smell of a sick person and sewage.

The infected seem to process what ever information comes from the senses but they have a lack of higher level of understanding and also natural instincts like avoiding getting hurt or having any kind of social behaviour. They move in herds that are most likely created by coincidence, when they are attracted by healthy humans. It's not known what lures them but guesses have been made for human smell, sounds, warmth, blood and disgusting hunger for human meat.
Most of the infected move especially during the night time. Many of the cured humans have found to have problems with seeing especially in brighter light which might be the reason. During the daylight many have eyewitnessed especially the longer time infected to stand against walls or hide in shadows or empty buildings to avoid as much light as they can. They stay still unless they are harassed intentionally - this makes them exceptionally dangerous. In a blind furious state they attack absolutely anything nearby was it a human, an another infected, an animal or a tree.

The infected sometimes carry even guns with them on holsters depending on what they were doing before turning. How ever, they never really use any of the equipment they have and if they do, they frantically toss things that comes to their reach.¹ This is dangerous though, since despite their current state, some of them have been real jocks as humans. They also might throw sharp or heavy things.
Abilites all in all reflect more or less weakly what kind of person the infected once was. Some are faster, stronger or more dogged than the others and vice versa.

¹⁾  The mutation of the "zombie illness" in New Zealand doesn't block so much of the nerve systems and some of the infected there have been said to use guns, knifes and other equipment to bring down healthy humans.

The infected come from varied histories which naturally has an effect on their skills and appearances. They are often being infected by people they know, such as family members, friends or neighbours.