This course is intended for anyone who is fascinated by the capabilities of large language models and generative artificial intelligence and wants to delve into the subject beyond just the level of the average user. Together we will get to know transformers, the basic building blocks of modern language models, introduce the most famous architectures and show how large language models can be used for various applications. No third-party paid account is required for hands-on exercises. We will be using open source models which, when used correctly, are as good as the biggest commercial models.