密铺（Tessellation）或称平面填充、细分曲面（subdivision surface），是指把一些较小的表面填满一个较大的表面而不留任何空隙。在数学上，密铺可以推广到更高的维度，称为空间填充。

有规律的密铺具有周期性的重复模式，较特殊的种类有平面正密铺由正多边形组成，而且是由同一种形状独立完成整个密铺，和平面半正密铺与拟半正密铺用不只一个正多边形完成密铺，前者在每个角落都有相同配置，后者则是周期性的重复模式。有规律的密铺形成的图案可分为17组。缺乏重复图案的密铺被称为“非周期密铺”。非周期性平铺使用一些较小的表面填满一个较大的表面而不留任何空隙，但由于每一片的形状皆不相同，以致无法形成重复图案。

A tessellation of a flat surface is the tiling of a plane using one or more geometric shapes, called tiles, with no overlaps and no gaps. In mathematics, tessellations can be generalized to higher dimensions and a variety of geometries.

A periodic tiling has a repeating pattern. Some special kinds include regular tilings with regular polygonal tiles all of the same shape, and Semiregular tilings with regular tiles of more than one shape and with every corner identically arranged. The patterns formed by periodic tilings can be categorized into 17 wallpaper groups. A tiling that lacks a repeating pattern is called "non-periodic". An aperiodic tiling uses a small set of tile shapes that cannot form a repeating pattern. In the geometry of higher dimensions, a space-filling or honeycomb is also called a tessellation of space.