FOR - DURING - WHILE

For, during and while are used in time expressions.

FOR	For is followed by a length of time : for one hour. It answers the question : How long? I have been standing here for 10 minutes. Tony is going to San Francisco for a week. My parents lived in London for 2 years. Have you been attending English classes for a long time?
DURING	During is followed by a noun. It means 'throughout the period' or 'in the course of' an action or event. During the summer I go to the beach as often as possible. Exercises were given to us during the lesson. The bank was robbed during the night. My grandparents often come to stay with us during the winter.
WHILE	While is usually followed by a subject and a verb. It means 'during the time that an action is taking place'. They held hands while they were watching the film.. The students took notes while the teacher was speaking. We'll collect some seashells while we're walking on the beach. Alex phoned while you were out. It is often possible to drop subject + be : I generally listen to music while driving to work. Sam twisted his ankle while playing tennis. While can also be a noun which means 'a period of time'. I spoke to the neighbour for quite a while yesterday. It's been a while since I read that book.