[1] The functions combined vary, but a common variant is to incorporate an extra storage function into chair, tables, and so forth, making them so-called storage furniture.
[2] It more efficiently uses up living space.
[3] Lack of space can be an important reason for choosing such furniture, but combination furniture is also seen in larger homes for more space-efficient utilization.
[1] Historically, furniture with transforming mechanisms was called "mechanical furniture".
Some common examples of multifunctional furniture are: