uses of deployed contracts:

By calling thrugh extranal ssource like website or server:

CCI’s:

• CCI’s is stands for Cross Contract Invocation, which is used for calling functions of external deployed contract in the current contract.

Interface:

• Before we call a contract, we need to define the structure of the contract in an interface.
• A way to define the external function without providing their implementation.

Properties of Interface:

• The function should be external(even it is public in contract).
• It is only the function declarations not the function implementation.
• It does not contain any state variable and constructor.
• It can only inherit other interface.

e.g.

this is a base contract.