how to join like a "In A but not in B" operation?

[Richard]

hi,
 
how can I join two tables A and B so that the result is "In A but not in B"?
 
let's take an example, say, the column to identify record is id.
e.g.
 
  select A.* from A join B on (A.id = B.id)
 
thanks.
Richard