Turtle species can be divided into four major categories: aquatic turtles, tortoises, semi-aquatic turtles, and sea turtles.

In biological terms, turtles belong to the class Reptilia and the order Testudines, and are one of the long-standing extant groups of reptiles. Their bodies are covered by a hard shell, and when in danger they can retract their head, limbs, and tail into the shell. Divided by living environment and habits, turtles can be broadly grouped into four major categories: aquatic turtles, semi-aquatic turtles, tortoises, and sea turtles, which differ noticeably in appearance, diet, and keeping methods.

Aquatic turtles are the most common type in captive keeping, with representative species such as the Chinese pond turtle, red-eared slider, Chinese stripe-necked turtle, and yellow pond turtle. They spend most of their time in water, are good swimmers, and have relatively omnivorous diets. Tortoises have stout, columnar limbs and a high, domed carapace; common ones include the Myanmar brown tortoise, African spurred tortoise, and leopard tortoise. They feed mostly on plants and prefer dry, warm environments. Semi-aquatic turtles fall between the two; the Chinese box turtle is a typical example, able to move about on land while also favoring humid forest-floor environments. Sea turtles, by contrast, live in the ocean their entire lives, with limbs evolved into flippers; along China's coast, species such as the green sea turtle and hawksbill turtle can be seen.

Family turtle keeping is mostly for ornamental purposes. Aquatic turtles need a sufficient body of water and a basking platform, regular water changes to keep the water clean, and sunlight or lighting for basking to help them synthesize calcium and prevent soft shell. Tortoises place more emphasis on controlling temperature and humidity; feeding them fresh vegetables and pasture grass daily is enough. Turtles have a relatively slow metabolism and generally long lifespans, so before keeping one you should be mentally prepared for long-term care.

It should be noted that many turtles are protected animals; for example, the vast majority of tortoise species are included on protection lists, and catching, buying, selling, or keeping them privately without a permit is illegal. Before choosing a species, you should first understand the relevant laws and regulations, select individuals of legal origin, and do a good job of routine management and disease prevention so that the turtle can grow up healthily.