Propagation techniques are methods used to grow new plants from existing ones. Common techniques include seeds, cuttings, layering, and grafting. Each method has its own advantages and is suitable for different types of plants. For example, cuttings involve taking a part of a plant, like a stem or leaf, and encouraging it to develop roots. Another popular technique is layering, where a branch is bent to the ground and covered with soil to promote root growth while still attached to the parent plant. Grafting involves joining parts of two plants together to grow as one, often used to combine desirable traits from both.