An outdoor or patio heater uses infrared (also known as radiant) heat to directly warm people within proximity of the heater. These come as electric infrared / patio heaters, gas heaters or firepits/chimineas.
Gas heaters are highly inefficient as they consume a high amount of gas for the relative heat output and are very bad for the environment due to the high CO2 levels. They are also very inconvenient with heavy gas cannisters or complex installation.
Fire pits / chimineas are a bit better for the environment and can create a nice atmosphere. However, they are usually very smelly and of course need constant attention, supplies of wood etc and are not practical for most urban areas or anything more than occasional use.