The Hello World of HLSL shaders. Outputs a red pixel for every fragment

HelloWorldShader.shader

Shader "HelloWorldShader"
{
    // Parameters passed in through Unity
    Properties {
        _Color ("Color", Color ) = (1, 1, 1, 1)
    }

    SubShader {
        Tags { "RenderType"="Opaque" }

        Pass {

            CGPROGRAM

            // Tell the complier what function is the vertex and fragment shader
            #pragma vertex vert
            #pragma fragment frag
            
            // Include Unity specific functions
            #include "UnityCG.cginc"

            // Create a local variable for the property (note this matches name and type in the Properties above)
            float4 _Color;

            // Data structure the mesh. Automatically filled out by Unity
            struct MeshData {
                float4 vertex : POSITION;  // vertex position
                float2 uv : TEXCOORD0;  

                // Other data type annotations available; 
                // float2 someData1 : TEXCOORD1;  
                // float2 someData2 : TEXTCOORD2; // Increment for additional data, like diffuse, normal, lightmaps, etc
                // float3 normal: NORMALS;  // Normal of the vertex
                // float4 color: COLOR;
                // float4 tanget: TANGENT;
            };

            // Data structure for passing data from Vertex shader to Fragment shader
            struct Interpolators {
                //float2 uv : TEXCOORD0;  // data to pass to through
                float4 vertex : SV_POSITION; // clip space position
            };

            // The Vertex shader
            Interpolators vert (MeshData v) {
                Interpolators o;
                o.vertex = UnityObjectToClipPos(v.vertex);  // Converts local space to clip space
                return o;
            }

            // The Fragment shader
            float4 frag (Interpolators i) : SV_Target {
                return _Color;
            }
            ENDCG
        }
    }
}