HD Textures

HD Texture Packs (or HD Resource Packs) are packs that contain textures of a higher resolution than Minecraft's default resolution of 16x16 pixels

Technical
Minecraft uses a resolution of 16x16 pixels for most textures including blocks and items. In Resource Packs, textures can be made to be smaller or larger than 16x16 pixels. For block and item textures the only requirements are:


 * 1) Static textures must have an equal width and height (ie. 32x32 pixels)
 * 2) Animated textures must have a height equal to the width time the number of frames of animation (ie. 32x64 pixels for two frames)

When making a Resource Pack there are some other points to keep in mind:


 * Various resolutions can be mixed in the same pack. For example, one block can be 32x32 pixels and another block can be 64x64 pixels.
 * Most textures other than blocks and items will be stretched to fit.

Common Sizes
Custom resolution textures offer several benefits such as higher quality, more creative freedom, and even reduced lag.

Resource Packs are often categorized by the resolution of blocks in the pack. A "64x" Resource Pack means the blocks have a resolution of 64x64 pixels. Most packs are created with the texture resolution as a power of 2 (8, 16, 32, 64, 128, etc.).

Packs come in a variety of resolutions. Small resolutions such as 8x can be used to reduce lag on older systems. Larger resolutions such as 32x or 64x can often be run without a significant decrease in performance. Resolutions like 512x, 1024x, and higher are often combined with shaders to create photo-realistic textures.