There are a lot of shaders. Some of them are very realistic, but you need a very powerful CPU and GPU.
Shaders add reality to the game. They make water more realistic, the grass and leaves begin to move. Beautiful and realistic rain appears. In powerful shaders appears effect of after rain water on the blocks. It has beautiful reflection. Beautiful shades appear. Sun becomes more realistic.
In some shaders we can see a very smooth effect when you approach the light. Sometimes you can meet even more amazing features.
If you download forge-optifine, you can add mods with your shaderpack.
I have two my favorite shaders: BeyondBeliefLegacy and Chocapic13 v9 the most demanding version.
Here you can choose your favourite shaders. Below this video there is a link to download all shaders.
By Alex R