Optifine​

Optifine allows more graphical options, such as shaders, connected textures, ... while usually also increasing the performance of the game substantially.

For complete information you can visit OptiFine

Installation​

Prerequirement​

You need Java installed on your computer. Minecraft comes with an isolated java runtime that gives java capabilities, but only to the Minecraft launcher.

In order to execute the .jar files, you need a Java Runtime Environment.
You can download the Java JRE at https://www.java.com/en/download/
Once installed, .jar files can be executed on your computer, which is required to install Optifine.

Install Optifine​

Installation should be swift. You can double-click the jar which will attempt to install Optifine to the default Minecraft location. If you use a custom location you will just have to adjust the program, which can be easily done.

Optifine will check if Minecraft is installed in the default location and set the installation path if Minecraft is in its default location.

Click Install to install Optifine.
A popup "Optifine installed successfully" will pop up.

Using optifine​

When you start your Minecraft Launcher, you should see the version "Minecraft xxx - Optifine" which will run Optifine.