Large Language Models for Code (LLMCs)—AI systems trained on extensive code repositories—are reshaping software development by enabling developers to address complex tasks with greater efficiency. These models support a range of activities, from generating code to identifying bugs and optimizing architectures, but their effective use requires a deep understanding of their capabilities and limitations. This e-book provides a structured exploration of LLMCs, offering developers practical guidance and research-backed insights to integrate these tools into their workflows.