A joint family is a family which consists of all of your aunts, uncles, cousins and grandparents. In other words, it is a family where your whole family lives under one roof.
Some of the advantages of having a joint family are listed here...
1) Bonds become stronger. Day to day activities are done with them, thus allowing us to know them better.
2) There is no need of internet and the help of outsiders, as there are many people at home specialized in many different subjects to help you out.
Some disadvantages are listed here...
1) The expenses might take a huge increase. Food, electricity, facilities are some of things that are now becoming very expensive.
2) Space might decrease due to many people living in the same house. And buying a big house might not be in everyone's budget.
Hope I helped..