> For the complete documentation index, see [llms.txt](https://notes.adarshdubey.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://notes.adarshdubey.com/deep-learning/topic-wise-notes/back-propagation.md). # Back Propagation These notes are from the video series of [CampusX YouTube](https://www.youtube.com/@campusx-official)' playlist: [100 Days of Deep Learning](https://youtube.com/playlist?list=PLKnIA16_RmvYuZauWaPlRTC54KxSNLtNn\&si=ytwvd2InN9ECzXVX). I have just written these for myself and for others to refer in future. In this notes, we'll have a try to understand what is back propagation. You can find the first video of the series [here](https://youtu.be/6M1wWQmcUjQ?si=oOpHrJXlibxDZyYU). Prerequisites: * Forward propagation * Gradient descent * Notations: Notes are divided into 2 parts: * [What is back propagation?](/deep-learning/topic-wise-notes/back-propagation/what-is-back-propagation.md) * [How does it work?](/deep-learning/topic-wise-notes/back-propagation/how-does-it-work.md)