The tape measure is used as a usually extendable and flexible ruler. It is not hard and firm like the ruler, thus providing the advantage of measuring uneven surfaces. They come in various widths and lengths.
The typical construction consists of a box, with the tape measure (usually semi-flexible steel banding) is rolled up inside the box. The spring-loaded retraction mechanism allows the tape to be pulled out to the desired length and then it will retract back to the case automatically if released from your grip.
Often a switch-grip is placed on the side. When activated this keeps the tape measure in place until released. It is only when the switch is released that the tape will then return. The one-sided ruler is often seen in both the metric and imperial measurement systems.
In the fabric and clothing sphere, tape measures typically are non-metal and extremely flexible, have measurement marks on both sides and are usually not restricted to a container with a retracting mechanism.