Aragon Client DAOs are made up of tiny independent software programs, known as “smart contracts”. Together they build up an operating system that runs the DAOs. It is called aragonOS and is similar to MacOS or Linux.
The core of aragonOS is the Kernel, a brain of the DAO. There is also ACL, which ensures that only authorized accounts (People) and contracts (Programs) have permission to perform specific actions in an organization. For example it can enforce that only ANT token holders can vote on a proposal.
To expand functionality, DAO can install apps, developed for aragonOS. They will expand functionality and allow new actions for the members. You can add pre-built apps from Aragon or develop your custom applications.
Some examples of available applications that can be added to Aragon Client DAOs are Token, Voting or Finance apps. Yet there are many more available.