DLookup finds a single piece of data without having to create a recordset, etc.
For instance:
MVariable = DlookUP("Field you are looking for", "Table", "Criteria")
So you can retrieve this data with a single line of code.
It is a VERY handy function.
In PHP/SQL, it takes 5 lines of code (basically creating a query targeted on one field in one record)
I was just trying to see if there was a similar structure in PHP that did the same thing in one line.