The concept of a record

I found it hard to understand the concept of a record in Fortran I/O.

Here are some of the questions I have about it.
1. one record is equivalent to one line?

2. Each read, write or print statement deal transfer one record?

3. What if in one write statement I want output several values? Will
they be treated as one record, or splitted into several? For example:
write(12) U(:)
Notice that I want binary output, and the array U have many
components. So now, will U be written in one record, or many? Will the
output be on one line, or many?

Thanks in advance!
.