To see is to use your eyes in order to recognize things. We can see things even if we are not paying attention.
- Suddenly I saw a strange sight.
- I couldn’t see anything.
See can also mean understand.
- Did you see what I mean? (= Did you understand what I mean?)
We do not normally use the continuous form of see with this meaning.
- I can see a ship. (NOT I am seeing a ship.)
However, continuous forms of see can be used to talk about future arrangements.
- I am seeing your Dad tomorrow.
To look at something is to try to see what is there. It involves paying attention. Note that we can see something, even if we don’t want to see it. However, we can only look at something deliberately.
- I looked at the screen but I couldn’t see anything.
- He looked at her with suspicion.
When look has an object, it is normally followed by the preposition at.
- She looked at me. (NOT She looked me.)
When there is no object, we use look without a preposition.
- Look! (NOT Look at!)
- Look here! (NOT Look at here!)
- Look at him. (NOT Look him.)
The use of the preposition is optional when look is followed by a wh-clause.
- Look what you have done! OR Look at what you have done!
Watching involves paying attention and in that sense it is like look at. We watch things that change or develop.
- The police have been watching his moves for two days.
Watch is normally used with TV.
- ‘What were you doing in the morning?’ ‘I was watching TV.’
Both watch and see can be used to talk about films and TV programs.
- I saw an interesting program on TV yesterday. OR I watched an interesting program on TV yesterday.
See if / whether
See can be followed by an if-clause or a whether-clause. Look and watch cannot be used in this way.
- See if we can get a ticket for the show. (NOT Look if we can get a ticket for the show.) (NOT Watch if we can get a ticket for the show.)