Mozilla firefox is very old and famous browser . It does not require any introductiin, its name is only sufficient. It is browser which can open any site which cant be opened in other browser. But with time it doesnt improve. One of the problem with this is that, the downloading speed is low as compared to other. But the main problem is that it hangs a lot, which make it difficult to use. Although it has many useful feartures which is required in an browser such as background downloading and many more. But I dont prefer it at first place.