打底裤，又称内搭裤，是内衣的一种，为男性或女性所穿着的紧身裤，但通常大多数是女性穿着的，主要是因为女性着裙或衣料上裙质太薄都会有走光之虞，为了防止透光或被风吹起而看见内裤、阴部，所以女性穿着打底裤有较佳的屏蔽，在这种功能上也就有着安全防护的效果。

女性除了穿紧身裤，也可着裙子将紧身裤穿在里面，又或者改穿衬裙来取代安全裤，而且紧身裤本身也有着许多种颜色，常见的是黑色款。

打底裤一般都是由氨纶、尼龙、棉或是聚酯混纺而成，不过也可能是羊毛或是丝绸材质。有时会将打底裤直接穿在外面，不过一般外面会用其他衣物盖住部份的打底裤，例如裙子、长的T裇、短裤等，或者是用长裙完全覆盖住打底裤。

Leggings are a type of skin-tight garment that covers the legs and may be worn by both men and women. Formerly, leggings were two separate garments, one for each leg.

Modern leggings are typically made from a blend of lycra (aka spandex), nylon, cotton, or polyester blend, but they can also be made from wool, silk, and other materials. Leggings are available in a multitude of colors and decorative designs. Leggings are sometimes worn fully exposed, but are more traditionally worn partially covered by a garment such as a skirt, a large t-shirt, shorts, or fully covered by an outer garment, such as a full length skirt.