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+# 01. Core Concepts
+
+Understanding the three core elements of LangGraph.
+
+## Overview
+
+LangGraph is a framework that models agent workflows as **graphs**. By decomposing complex workflows into **discrete steps (nodes)**, it achieves the following:
+
+- **Improved Resilience**: Create checkpoints at node boundaries
+- **Enhanced Visibility**: Enable state inspection between each step
+- **Independent Testing**: Easy unit testing of individual nodes
+- **Error Handling**: Apply different strategies for each error type
+
+## Three Core Elements
+
+### 1. [State](01_core_concepts_state.md)
+- Memory shared across all nodes in the graph
+- Snapshot of the current execution state
+- Defined with TypedDict or Pydantic models
+
+### 2. [Node](01_core_concepts_node.md)
+- Python functions that execute individual tasks
+- Receive the current state and return updates
+- Basic unit of processing
+
+### 3. [Edge](01_core_concepts_edge.md)
+- Define transitions between nodes
+- Fixed transitions or conditional branching
+- Determine control flow
+
+## Design Philosophy
+
+The core concept of LangGraph is **decomposition into discrete steps**:
+
+```python
+# Split agent into individual nodes
+graph = StateGraph(State)
+graph.add_node("analyze", analyze_node)  # Analysis step
+graph.add_node("decide", decide_node)     # Decision step
+graph.add_node("execute", execute_node)   # Execution step
+```
+
+This approach allows each step to operate independently, building a robust system as a whole.
+
+## Important Principles
+
+1. **Store Raw Data**: Store raw data in State, format prompts dynamically within nodes
+2. **Return Updates**: Nodes return update contents instead of directly modifying state
+3. **Transparent Control Flow**: Explicitly declare the next destination with Command objects
+
+## Next Steps
+
+For details on each element, refer to the following pages:
+
+- [01_core_concepts_state.md](01_core_concepts_state.md) - State management details
+- [01_core_concepts_node.md](01_core_concepts_node.md) - How to implement nodes
+- [01_core_concepts_edge.md](01_core_concepts_edge.md) - Edges and control flow