Immediate family: you, your husband/wife, children, parents, brothers, sisters
Extended family: aunts, uncles, cousins, nephews, nieces, grandparents, grandchilren
My immediate family is quite small, because I'm the only child. My mum is one of five children, so I have a lot of cousins, who are kind of like my brothers and sisters.
There are 6 people in my immediate family: my parents, my brother and his wife, my sister and me. I have a lot of other relatives, but they live in Canada so we don't see them often.