SimpleColorShader.shader

// reference: http://danjohnmoran.com/Shaders/101/

Shader "Custom/ShaderCrashCourse/SimpleColorshader"
{
	SubShader
	{
		Tags
		{
			"PreviewType" = "Plane"
		}
		Pass
		{
			CGPROGRAM
			#pragma vertex vertexFunction
			#pragma fragment fragFunction
			#include "UnityCG.cginc"

      // Input Data 
			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

      // Output Vertex Data 
			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 position : SV_POSITION;
			};

			v2f vertexFunction (appdata _in)
			{
				v2f _out;

				_out.position = UnityObjectToClipPos(_in.vertex);   // Convert to screen position
				_out.uv = _in.uv;                                    // return the UV mapping

				return _out;
			}

			fixed4 fragFunction (v2f _in) : SV_Target
			{
				float4 color = float4(_in.uv.x, 0.5, _in.uv.y, 1);		// the color is depend the uv position on the mesh
				//float4 color = float4(_in.position.x, 0, _in.position.y, 1);		// the color is depend the uv position on the mesh
				return color;
			}
			ENDCG
		}
	}
}

SimpleTextureShader.shader

Shader "Custom/ShaderCrashCourse/Emptyshader"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
	}
	SubShader
	{
		Pass
		{
			CGPROGRAM
			#pragma vertex vertexFunction
			#pragma fragment fragFunction
			#include "UnityCG.cginc"

      // Input Data 
			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

      // Output Vertex Data 
			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 position : SV_POSITION;
			};

			sampler2D _MainTex;

			v2f vertexFunction (appdata IN)
			{
				v2f output;

				output.position = mul(UNITY_MATRIX_MVP, IN.vertex);   // Convert to screen position
				output.uv = IN.uv;                                    // return the UV mapping

				return output;
			}

			fixed4 fragFunction (v2f IN) : SV_Target
			{
				// sample the texture
				fixed4 fragColor = tex2D(_MainTex, IN.uv);          // return color for each pixel

				return fragColor;
			}
			ENDCG
		}
	}
}