For questions about the Open Source aspects of the software that makes up the Stack Exchange Network. Do not use this tag for questions about unrelated or your own open source projects.
Some of the components used by Stack Exchange are open source. Use this tag if you have questions about those components and/or if you want to discuss if specific components can be considered to be open sourced.
Consider if the architecture tag is relevant for your question as well.
Do not use this tag for questions about open source that is not related to SE in anyway.