The height group of car seats is based on the European ECE R129 (i-Size) standard, which replaces the previous classification according to the weight of the child. This standard classifies car seats based on the height of the child and also takes into account the child's age and direction of travel. The most common groups include seats for children between 40 and 75 cm (newborns), 61-105 cm (toddlers) and over 100 cm (larger children, often with the option of using a vehicle seat belt). This classification increases safety because it better matches the actual dimensions and needs of the child.