Ground squirrels are members of the squirrel family of rodents (Sciuridae), which generally live on or in the ground, rather than trees. The term is most often used for the medium-sized ground squirrels, as the larger ones are more commonly known as marmots (genus Marmota) or prairie dogs, while the smaller and less bushy-tailed ground squirrels tend to be known as chipmunks (genus Tamias). Together, they make up the "marmot tribe" of squirrels, Marmotini, a division within the large and mainly ground squirrel subfamily Xerinae, and containing six living genera. Well-known members of this largely Holarctic group are the marmots (Marmota), including the American groundhog, the chipmunks, the susliks (Spermophilus), and the prairie dogs (Cynomys). They are highly variable in size and habitus, but most are remarkably able to rise up on their hind legs and stand fully erect comfortably for prolonged periods. They also tend to be far more gregarious than other squirrels, and many live in colonies with complex social structures. Most Marmotini are rather short-tailed and large squirrels. At up to 8 kg (18 lb) or more, certain marmots are the heaviest squirrels.

The chipmunks of the genus Tamias frequently spend time in trees. Also closer to typical squirrels in other aspects, they are occasionally considered a tribe of their own (Tamiini).

The ground squirrel is especially renowned for its tendency to rise up on its hind legs, usually whenever it senses nearby danger, or when it must see over tall grasses. The squirrel then curls its paws flat against its chest and sends a screeching call to warn other family members about the presence of predators.