An offering is something that is freely given above and beyond your tithes. These funds are used to help the church with bills as well as helping others within the community.
God expects us to give to Him from our first fruits or wages. The word tithes literally means 10%. These tithes are to be used in the helping of others.
All we have to do is look at the Levites to see what is expected.
The Word Of God
Envy thou not the oppressor, and choose none of his ways. For the froward is abomination to the LORD: but his secret is with the righteous.
