Tube fittings connect runs of tubing (for in-line, offset, multi-port, and mounting configurations) to other tubing sections, pipe, hose, or other components. Systems are typically configured with straight sections connected by fittings or specially formed connections and joints.

Fitting construction and material specifications are application-dependent; consulting the fitting supplier is typically a wise route for optimizing component selection. However, most tube fittings correspond to either hydraulic or pneumatic systems.