Oil heating systems are probably the most commonly used ones in households nowadays, regardless of the specific subtype of heating system (e.g. air- or water-based). In an oil heating system, a centralized device heats up either the water or air to the desired temperature, using specialized oil as its fuel. The most common alternatives to this type of heaters are either coal or electricity based ones, though both are seeing less and less popularity in recent times, due to the availability and cost of oil compared to them.
Oil heating systems are most commonly used with water to provide the actual heating, when utilized at home. The idea is simple: a boiler holds the water that is dispersed throughout the household, and a device draws oil into the boiler to provide fuel for its combustion when it's needed. In most cases, this process will be entirely automated - thanks to devices known as thermostats, the system is able to adjust itself according to the house's current temperature, boiling the water when it gets too cold and turning off the flames when the appropriate temperature has been reached.
Heating systems that utilize oil tend to be a bit more complicated in their design than coal and even electricity based ones, as they need to apply a fine degree of control over the amount of oil being used, in order to prevent accidents or overuse of resources. The thermostat is a vital part of the process and needs to be regularly checked for any problems or malfunctions, and the system itself requires a bit more maintenance as a whole.
What are the advantages though? Well, space is one of the biggest ones when you compare it to a coal-based system - apart from having to dedicate a lot of room for storing the coal, coal furnaces also tend to take up a lot of space by themselves. Compare that to the small tank of an oil-based heater and the small-sized heater itself, and you get a system that's very efficient in utilizing the available space. Of course, this is somewhat of a moot point when you compare it to an electric heater, but even those have their noticeable disadvantages compared to an oil-based heater - they require a lot of power to provide the necessary heating, and the long-term costs of running such a system compared to using an oil-based one are tremendous, which is one of the main deciding factors in consumers picking those systems, as research indicates.
Given all that, considering how customizable oil-based heating systems are and how they can be adjusted to work with most commonly used home heating systems, you really can't go wrong in picking this type of system to provide your household with appropriate heating. Yes, you'll have to dedicate some time for its maintenance, but then again, that's valid for other types of heating systems as well and shouldn't really be considered a disadvantage in itself.