what is ufo?

This is the main issu of this word .sometimes wee feel that there is another types of man too .they are alive and loooking our actives but it may not be right because here is no anything which can be tell u fearly .but it is sure that some undefined flying object is here in the word .which may be the the flying object of the some developed country and they used it to observe the actives of the other country.so we can't tell the truth till than when the all developed country is set into the unity .but if here is exitence of the other planet's animal or man then they may be strong or power ful then us and they may have developed then us .there is also other probability is there may be other planet which may not have developed then us.