Backstory: a few months back, I wrote a blog post on how agents, then called chatbots, used to be defined: https://sachindixit.co.in/2025/12/05/chatbots-before-llms/. This was supposed to be followed by a detailed post on how agent creation has evolved since then.
In the meantime, agents became a buzz and faded a bit 🙂 I also started teaching our engineers about it, presented them at different meetups and conducted workshops. That evolved into a neat code repo with a do-it-yourself agent course. I also had a separate repo with my notes in textbook style on what the concepts meant. Now I have merged them together and am making it public.
As an author, I find it useful, but I must say the field is evolving fast; there is a lot to be added in the textbook. Moreover, the prose is my opinionated take on agentic everything; the code/concept ladder represents how I would teach concepts from the ground up. So have a look, and I hope it helps you .