Only in the last decade a product called patio heater gained the popularity. Probably that happened due to the fact that many countries validated the non smoking law and put all the smokers outside the restaurants and bars. Poor people are drinking and smoking outside at freezing temperatures. It is really a great solution when they can gain just a little warmth, standing close to the outdoor patio heater. And even the coldest temperatures are not such a huge issue any more.
Gas or electric patio heater?
Patio heaters are the most appropriate solution for outside events, and for the outdoor spaces where we spend a lot of time. So if you have a roof, and you want to spend much time outside your house even in winter, getting a patio heater would be a great solution for you. On the market there are
many different products for your patio. So you have to think really thoroughly about all the options. First of all it is really important to decide what kind of heater you would want.The most common are the liquid petroleum gas heater and the electric gas heater. So the resource of heating depends on a price. If the electricity is cheaper then liquid petroleum gas, you should definitely pick the electrical heater. Nevertheless you should be careful that this heater will fit in the atmosphere. So when choosing one of these products, be aware that is not very good to have a huge heater in a small
patio. You should not make this heater a centre of attention of your outside space. The best would be if you could fit this heater in nicely, so it remains heating and doing its basic function as well as not being the work of art of the terrace. You have many choices and designs available, and the best way to search for them is on the internet. If your patio is designed in modern way, you should consider getting stainless steel product, or even a pyramid shaped heater. If you want to create a bar atmosphere, you can buy a heater in a shape of a bar table, on which you can easily put some drinks and the bottom part will perform a heating task.
Due to the fact that such a heater is a technical product, you should consider quality very much. 
Apart from the quality you should also choose the product which has a spare parts network and supply taken care of. It might happen that you would need a spare part urgently, and if you take a product without spare parts sales network, you could stay with your broken heater in the cold, alone.
Take your time and think really before making the decision which patio heater to buy, at the end of the day, you are the one, that needs it. There is a lot of online stores offering patio heaters like this one here.