semantic kernel
**Semantic Kernel** is **Microsoft's** open-source SDK for building AI-powered applications that integrate **LLMs with conventional programming**. It provides a structured framework for orchestrating AI capabilities alongside traditional code, plugins, and external services.
**Core Concepts**
- **Kernel**: The central orchestrator that manages AI services, plugins, and memory. Acts as the "brain" of your application.
- **Plugins (formerly "Skills")**: Modular units of functionality that can be either **semantic functions** (LLM prompts with structured inputs/outputs) or **native functions** (regular code in C#, Python, or Java). These are the building blocks of AI workflows.
- **Planners**: AI-powered components that take a user's goal and automatically create a **plan** — a sequence of plugin calls — to achieve it.
- **Memory**: Built-in support for **vector-based semantic memory** for context retention and retrieval.
- **Connectors**: Integrations with LLM providers (**OpenAI, Azure OpenAI, HuggingFace**) and other AI services.
**Key Features**
- **Multi-Language**: Available for **C#** (primary), **Python**, and **Java**.
- **Enterprise Ready**: Deep integration with **Azure** services, enterprise security patterns, and production deployment best practices.
- **Prompt Engineering**: Built-in templating system for creating reusable, parameterized prompts.
- **Function Calling**: Native support for LLM function/tool calling, connecting model outputs to executable code.
**Use Cases**
- **Copilot Development**: Building custom copilot experiences for enterprise applications.
- **Process Automation**: Orchestrating multi-step workflows that combine AI reasoning with business logic.
- **RAG Applications**: Combining retrieval with generation using Semantic Kernel's memory and plugin systems.
Semantic Kernel is a core component of Microsoft's **Copilot Stack** and is used internally to build Microsoft's own AI-powered products. It emphasizes **responsible AI** patterns and enterprise-grade reliability.