Easy to grow, they are very adaptable and Inexpensive to buy
Cacti and succulents, some well-known ones would be Aloe vera, Echeveria, Gymnocalycium, Haworthia, Kalanchoe, Sansevieria and Opuntia.
Habit
A wide range of shapes and sizes some do flower but most are bought for the cute appearance.
Slow growing, you can fit a nice collection on your windowsill.
They have thick fleshy stems, that store water, they will grow taller and wider but only slowly.
Some have sharp spines and may not be suitable for children.
Temperature
They are very adaptable, happy at room temperature but will also survive lower temperatures.
Watering
In warm conditions, especially through the summer water often but allow them to dry out between each watering. In a cool room and during the winter you can allow the compost to dry out for long periods before watering.
Positon
Only happy in the sun, they might stand light shade but the plant will lean towards the light. A south-facing windowsill that would burn most houseplants is okay for cacti and succulents.
Very tough, happy in full sun and fun to grow.
Very few bad habits, not happy in the shade, the sharp spikes are not child-friendly.