RaycastHit2D.normal

Description

The surface normal of the detected Collider2D.

When the physics query detects an intersection of a Collider2D at a specific RaycastHit2D.point the normal is the surface normal of the Collider2D at that position. A surface normal is a vector perpendicular to the collider surface edge in a direction pointing away from the collider.

Additional resources: RaycastHit2D.point.

using UnityEngine;

public class ExampleClass : MonoBehaviour
{
    public Vector2 direction;

    void Update()
    {
        // Cast a ray in the direction specified in the inspector.
        RaycastHit2D hit = Physics2D.Raycast(transform.position, direction);

        // If something was hit, draw a line from the hit position in the direction of the surface normal.
        if (hit)
            Debug.DrawLine(hit.point, hit.point + hit.normal, Color.yellow);
    }
}

Note: If a hit starts occuring inside a collider, the collision normal is the opposite direction of the line/ray query.