Your collected and produced goods must be stored somewhere.
There are 5 buildings which can be built for this purpose:
There is not a limit on the number of storage buildings you can possess as long as you can afford the building and there is space to build on.
Since storage items can be upgraded, overlapping a new storage item over another (even by just a little bit) will remove the existing item and place a new item to build. During the build of an upgrade is the ability to store goods not available for that particular stockpile.
The new building doesn't have to be build on top of an existing one!