Polyester and cotton, which combines the properties of natural and synthetic fibres, is one of the most common blended fabrics. Natural fibres are sourced from plants and animals and require only manual separation and recombining for the fibres to be useable. Synthetics are scientifically developed from chemicals such as petroleum and require heavy processing to create the fibres.
Cotton is breathable, light and soft, making it very comfortable to wear as clothing against the skin. However it can also wrinkle or shrink when washed. Polyester is strong, doesn't wrinkle or shrink and holds colours well. However, it doesn't breathe and can be uncomfortable and smelly to wear.
Blending these two fabrics creates a material that is comfortable, resistant to wrinkles and holds its shape and colour well. Polyester and cotton has been a popular choice for business shirts as it is comfortable to wear each day but is easy to care for and lasts a long time.