Convection heaters use special coils to quickly heat the air up and small fans to circulate the air around the room. Most of them feature a thermostat that keeps the air at the desired temperature.
Ceramic heaters have a ceramic disc as their heating element. For their small size, they can provide you with a good amount of heat.
Oil-filled heaters, also called radiators, feature a sealed reservoir filled with special oil. A heating element heats the oil, which can stay warm for a long time after the heating element is turned off. Most of them also include thermostats that turn the unit off when the air reaches desired temperature and back on when it cools down.
Baseboard heaters radiate the heat upwards, heating the air right above them. If one is placed under a window (or somewhere where drafts are common), the rising current of hot air will meet with a cold stream coming into the room, warming it and spreading it around.
To learn more about different types of heaters and for hints on how to choose a heater that is right for you, please visit our Space Heaters Information Page.