The term "generalised anxiety disorder" (GAD) refers to a condition characterised by excessive worry. In some ways, the term "tension disorder" is a better one - this is a condition characterised by both mental tension (e.g. worry, irritability) and physical tension (e.g. muscle tension, insomnia).
The particular symptoms of GAD may differ somewhat from person to person. For example, some people may experience primarily cognitive symptoms (i.e. worry), while in other people the bodily symptoms (e.g. aches and pains) are experienced as the main problem.