For the few people who have wondered about this, wonder no more!
When it comes to Public Service Vehicles, there are two main modes of transportation in Kenya. There is the formal bus sector and the more or less informal matatu sector.
Matatus, or “mats” or “mathrees” are vehicles for public transportation, ranging from the small mini-van size to large buses. Whether it is a “matatu” largely depends on the formalization. Some big buses are considered matatus because they are not part of the formal bus sector, even though they are technically buses.
At a cursory glance, the easiest way for a visitor to identify if it is a bus or a matatu is by observing the design. Formal bus companies tend to have drab, uniform colours with uniform company names written on the side; and while they may play videos on screens inside for entertainment, they rarely play loud music. Matatus are the exact opposite. They tend to be loud and colourful, with shouty graphics and music to attract the young, hip crowd. This is especially so in Nairobi, where neighbourhoods have bragging rights over how amazing their matatus are.
Mini-vans used for public transportation, on the other hand, are always matatus.
The graphics vary over a wide range of topics, but generally tend to reflect the overall hip culture. What is new and hot can easily become part of a matatu's graphic. There are artisans who are dedicated to the art of "pimping" matatus, and earn a living from it.
The matatu sector used to be almost completely unregulated, but they have been forced to adopt regulation. Although there were rules on their appearance and the conduct of the driver and tout, they were not enforced. Matatu drivers and touts can be rowdy and have been known to be a menace on the roads. In a bid to get the most money, they can drive very fast and are sometimes reckless.
All Public Service Vehicles are now required to install a speed governor, and their drivers and touts required to wear uniforms, in addition to not having a criminal record. They are also required to be part of a Savings and Credit Cooperative (SACCO) or part of a larger company in order for them to be easily tracked. The SACCO and company names are also usually part of the graphics.
Either way, matatus have maintained the matatu culture. It is strong amongst Nairobi’s youth, with many not willing to be caught dead in a less-than-cool matatu.