Three subspecies are described,[2] the most recognizable of which is the red-eared slider (T. s. elegans), which is popular in the pet trade and has been introduced to other parts of the world by people releasing it to the wild.

These patterns and colors in the skin and shell fade with age until the carapace is a muted olive green to brown and the plastron is a dull yellow or darker.

The carapace is oval with a bit of rounding and a central crest with knobs, but these features soften and fade with age, adults being smoother and flatter.

Groups of sliders, sometimes quite large, as well as many other types of less abundant freshwater turtles, are often seen basking and sunning on logs, branches, and vegetation at or even well above the water's surface, but they readily and quickly scramble if they sense danger, shooting back in and darting away to safety underwater.

[6] By the first quarter of the 21st century, this species has spread widely across the waters of Europe and Southeast Asia, and is also found in the Urals and Siberia.