Breadth-First Search

## How Breadth-First Search Works

BFS explores a graph level by level. It starts at the root and explores all neighbors before moving to the next level of neighbors.

### Algorithm Steps:
1. Start at the source node and mark it visited
2. Add source to a queue
3. While queue is not empty:
- Dequeue a node
- For each unvisited neighbor, mark visited and enqueue
4. Repeat until all reachable nodes are visited

### Key Characteristics:
- **Uses Queue**: First-In-First-Out (FIFO) data structure
- **Shortest Path**: Finds shortest path in unweighted graphs
- **Level Order**: Visits nodes level by level