Sod or turf is grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

 and the part of the soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

 beneath it held together by the root
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...

s, or a piece of thin material.

The term sod may be used to mean turf grown and cut specifically for the establishment of lawn
A lawn is an area of aesthetic and recreational land planted with grasses or other durable plants, which usually are maintained at a low and consistent height. Low ornamental meadows in natural landscaping styles are a contemporary option of a lawn...

s. However, in British English
British English
British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...

 such material is more usually known as turf, and the word "sod" is limited mainly to agricultural senses (for example for turf when ploughed), or avoided altogether, due to the alternative offensive meaning of the word "sod".

Sod (or turf) for lawns is grown on specialist farms. It is usually grown locally to avoid long transport and drying out and heat buildup of the product.