Defined Quote by Charles Petzold
“To a programmer, an operating system is defined by its API.”
About This Quote
Source Book: Code: The Hidden Language of Computer Hardware and Software, 2000
An operating system is defined by the functions it exposes to programs via its API.
In simple terms: OS defined by its API.
Key Takeaway
Focus on designing clear, stable APIs.
Themes
software design
abstraction
systems engineering
Mood
analytical
technical
Type
educational
technical
When to use this quote
- building new OS
- teaching OS concepts
- debugging interface issues
- ensuring backward compatibility
Key Concepts
API design
operating systems
software architecture
Questions to Reflect On
- How does API stability affect long‑term software maintenance?
- What hidden assumptions might an API hide?
A Different Perspective
Complex systems may hide deeper hardware constraints not captured by API alone.
![“The best way to prepare [to be a programmer] is to write programs, and to study great programs that other people have written. In my case, I went to the garbage cans at the Computer Science Center and I fished out listings of their operating systems.” quote by Bill Gates](https://sms4smile.com/quotes/img-quotes/c21/bill-gates-137_best-way_the-best-way-to-prepare-to-be-a-programm_1602708.jpg)
![“The self is defined psychologically as the psychic totality of the individual. Anything that a [person] postulates as being a greater totality than [oneself] can become a symbol of the self. For this reason the symbol of the self is not always as total as the definition would require.” quote by Carl Jung](https://sms4smile.com/quotes/img-quotes/251/carl-jung-274_defined_the-self-is-defined-psychologically-as-t_7148.jpg)
