Ampersand (&) operator in a SQL Server WHERE Clause

Sorry for the very basic question. What does the & operator do in this SQL

WHERE (sc.Attributes & 1) = 0 

sc is an alias for a table which contains a column attributes.

I'm trying to understand some SQL in a report and that line is making it return 0 entries. If I comment it out it works. I have limited SQL knowledge and I'm not sure what the & 1 is doing.