> For the complete documentation index, see [llms.txt](https://docs.casa.io/wealth-security-protocol/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.casa.io/wealth-security-protocol/system-design-principles/redundancy.md).

# Redundancy

An important principle of security engineering is defense-in-depth. **There should never be a single point of failure** that would allow for the whole system to be compromised. 

Redundancy is vital because no matter how much attention a team puts into secure engineering, perfection is beyond reach. Although we limit our use of third party software significantly, we do use a combination of both proprietary and third party software.  Vulnerabilities and bugs are regularly discovered even in fundamental software like operating systems that are developed and supported with multibillion-dollar engineering teams. Our system’s security should never rely on every single component being bug-free.<br>