In Etherscan, it is easy to find a contract. For example here is an example:
The web page says that the contract address is 0x80fB784B7eD66730e8b1DBd9820aFD29931aab03. I guess that the address is where the contract is created and is installed.
In the middle of the same web page, there is a Contract source code. But in the source code, there are several Contract declarations. Does it mean that more than one contract have been created and installed? Who has the Contract address in the top of the web page if there are more than one Contract?