This answer would be incomplete without a picturesque Marshrutka:

(courtesy Wikipedia)

A typical 13-pax GAZel painted in yellow and with route details.

Marshrutka. Dolmu? in Turkey. These are very similar things: something half way between a taxi and a bus. A shared minibus where the route, while exists, is more or less flexible -- the drivers will stop where there is no scheduled stop and sometimes even make small changes to the route even. You typically need to speak the local language so you can tell the driver (tell... yell!) where you want to get off -- scheduled stops are optional and as I mentioned you can ask for your own stop. It's typically cheaper than the ordinary bus. It's dangerous because the drivers drive fast, not always even waiting for the door to close and they take the money and give change -- often while driving. If you can call running amok with a vehicle "driving". So you need cash (although recently the Moscow Marshrutka began accepting the troika card). It doesn't help these things are often one duct tape away from the scrapyard. "Don't slam the door, it can break off and fall on your foot" is a real warning in some marshrutkas and you better believe it can.

The greatest danger of marshrutkis are lax regulations in terms of safety, driver qualifications and quality of service. Many small private companies will try to save on vehicle repairs and driver salaries, hiring underskilled drivers and forcing them to drive old rickety Gazelle minibuses for 12 hours a day. If such minibus gets into a nasty accident the driver will be arrested and face jail, however the owner will likely disappear only to start a new marhsrutka company at some other location.

Another "danger" you may face is that the drivers may sometimes alter or even cancel the route if they know no one in the bus would exit at a certain stop or if there aren't many passengers left. You'll need to stay alert, listen to the driver's announcements - in Russian - and be ready to answer questions about your destination so as not to miss it. That goes in contrast with the official buses that would normally follow the scheduled route even if there are no passengers left on the bus.

None of this means all marshrutkis are unsafe, and sometimes they're the only viable means of transportation to and from a remote location. However, unless you're a local, you may find the experience more stressful and will have a greater chance of ending up in a place you didn't mean to go to.

????????? (marshrutka) is like a private minibus, it is privately owned:

a way of public transport, private minibus. It is very common in Russia and other neighboring countries.#

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Dangerous?

They can be dangerous for some reasons:

On the bad side, they're crowded and speed excessively, increasing the risk of an accident.

From my experience of using them, it is fine.

Marshrutka vs bus

1. There are different routes, some people need the Marshrutka to get to their destination

2. As they are privately owned, you can't use a travel card equivalent on the, but you pay separately (you can use your Troika card)

3. You can choose your stops:

Lets say it is pouring with rain, a typical bus will drop you off at one of the many bus stops which could be some way from your home. However, on a Marshrutka you can request that you be dropped off anywhere on the route.

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Using one

Getting on:

So if you are waiting on a bus stop and you can see your marshrutka approaching, wave – give the driver a sign that you want to get in. Sometimes they stop also without this on more crowded bus stops (e.g. near metro stations), but better to be cautious.

Getting off:

When you are in the marshrutka, you paid the driver and you know what is your destination, it’s still not full success. Remember to ask the marshrutka driver to stop when you get close to your destination.

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Breaking the language barrier

Getting on

To get on, just wave, no problem and give the driver the fare specified.

Getting off

You can use Google Translate or similar and translate "??????? ?????????? ????? ????? (your destination)”. It means “Tell me please when we’ll be at…”. You can just play it to the driver and he should tell you when you are at the stop.

In the city in Ukraine were I live the ????????? (marshrutka) are basically just the buses that go around the city. They are privately owned - there are no publicly owned buses (although there are trolly buses) but regulated just like buses. They have a service contract with the city which specifies the routes, prices and how often they should run. There is no reason to think they are any less safe than they would be if there were publicly owned.

The word ??????? tends to used to refer intercity transport (although smaller vehicles will also be called ?????????).

In addition to other answers, some points that are specific to Nizhny Novgorod (I live in Nizhny myself).

Firstly, in many Russian cities the marshrutkas are small minibuses like in alamar's answer (basically, GAZelles). But in Nizhny much more common are PAZ buses. They are larger and allow for standing passangers.

Secondly, while in many cities you indeed can ask the driver to stop at any point along the road, in Nizhny this is quite uncommon. You press a special button inside a bus to indicate that you are going to exit on the next stop. Exiting in between is very uncommon. Similarly, you usually can stop (hail) the bus to enter it only on official stops.

Thirdly (and this is quite common to other cities too), marshrutkas and buses of the same route number can have a completely different route, e.g. a bus No 17 and a marshrutka No 17 can have nothing in common.

Marshrutkas were 'invented' in Soviet Union, I guess, to serve unpopular routes where many stops can have no passengers entering or exiting; hence the small buses and the requirement to indicate your intention to enter or exit to the driver. Then after the fall of planned ecomony it turned out that marshrutkas are realy profitable for private owners, I think because thay allow for smaller buses (thus smaller initial expenses to start business). So marshrutkas proliferated, while government-owned big buses endured all the harships of 90's. Nowadays many cities' governments try to limit marshrutkas in favor of big buses, but marshrutkas are still very popular in many places.

They are dangerous because the owners try to maximize profits by cutting expenses on regular mainteinance as well as by hiring inexperienced drivers; also they often go very fast to maximize the number of trips each bus make per day, thus also maximizing the profit.

The fact that there are buses and there are marshrutkas may indeed sound strange, but in fact it is not that uncommon all over the world to have similar public transort under different names. Think of German U-bahn and S-bahn for example. From Russian point of view, both are subway, and every Russian always asks what is the difference :)

As others have already correctly said, "marshrutka" is a colloquial version of "marshrutnoe taksi", that is, "routed taxi". This concept emerged in late 1930s when Moscow started operating a few ZiS-101 limousines between the city center and VSKhV (later VDNKh/VVTs, now again VDNKh), so that every proletarian could enjoy the luxury of a government limousine for an affordable price.

Russian legislation does not use this term since around 2007. Even before the legal concept of routed taxi was abandoned, there was a great variance in models of operation between cities. In fact, in many places real-world marshrutkas didn't comply with the regulations, and that was partially why bus legislation was revised to drop the term.

So, in modern parlance, the word "marshrutka" is a legacy colloquial term that means some kind of bus or minibus service, but the particulars are still variable.

For example, in Nizhniy Novgorod, marshrutkas are most often small or medium PAZ buses allowing for standing passengers and stopping at designated bus stops at request (passengers at stops wave hands, passengers alighting push a button above doors). In many other cities, marshrutkas are GAZelle or similar minibuses, where all passengers are expected to be seated (which is often not true) and can board and alight not only at designated bus stops but also between them.

In comparison to what is called "avtobus" (bus), marshrutkas have some of the following properties:

• Marshrutkas are privately-owned and operated.
• Avtobuses are government or municipality-owned and operated.
• Marshrutkas are operated by smaller class of buses than avtobuses.
• Marshrutkas only accommodate seated passengers.
• Marshrutkas only normally stop on request, sometimes given by voice, sometimes by pressing a button.
• Avtobuses normally always stop at designated stops.
• Marshrutkas can stop everywhere where driving rules permit, not only at designated stops.
• Marshrutkas operate without a published/imposed schedule; in particular, when departing from a major passenger-generating point such as a metro station or a mall, they may start on full occupancy.
• Avtobuses operate on a schedule.
• Marshrutkas are not integrated into a city-wide fare scheme.
• Avtobuses are integrated into a city-wide fare scheme.
• Marshrutkas are not allowing free rides (or reduced fares) for privileged social groups such as pensioners.
• Avtobuses allow free rides for privileged social groups such as pensioners (usually subject to limitations).

For each of these properties, there is at least one city where this property is true and at least one city where it is untrue. Note that these differences are most often not formally codified and constitute part of the culture of a given city.

It is a Soviet tradition which is still in force in Russia that different modes of transportation have independent numbering schemes. For example, a single street may be serviced simultaneously by avtobus 2, trolleybus 2, tram 2 and marshrutka 2, each service having its own route. When Russian legislation abandoned the term "marshrutka", existing lines had to be somehow distinguished between. In Nizhniy Novgorod, this was achieved by keeping the traditional prefix "T-" for marshrutkas and adding "A-" before avtobus bus lines. In other cities this might work differently.

In my city, we also have private buses - but they are not too different from normal buses, so people would just say "bus".

Historically, the main distinction between marshrutkas and public buses was that marshrutkas only accepted cash with a single fare for everyone, while public buses accepted city-issued season tickets and passes and provided discounts for children, students and the elderly. This distinction slowly washes away as private buses start to accept city passes in major cities, but in most places you're expected to have cash when boarding a marshrutka.

It should be noted that in some cities there are regular-size buses operated by private companies and not necessarily honouring city passes and fare reductions. Those can aslo be called marshrutkas, and can be distinguished by the itinerary number prepended or postfixed with a letter "K" which stands for "????????????" or "commercial". Some minibus-sized marshrutkas use the "K" letter too.