Active Thermography is a non-destructive material testing method, it relies on the use of infrared (IR) detectors in conjunction with some sort of artificially heating. Thereby, either a thermal pulse - pulse thermography (PT) - is applied or by a harmonic modulated way, the so-called Lock-in thermography (LIT). Depending on the chosen thermal excitation different material or component test are enabled. The PT approach allows the definition of certain thermal material properties, such as thermal diffusivity as well as the detection of inhomogeneities or defects within a specimen. LIT allows the tracking of a heat flow which is induced periodically by one or several modulated heating sources. Due to the elongated testing times in this approach larger areas may be inspected and this enables the detection inhomogeneities, which act as thermal barriers of the induced heat flow, on e.g. component level. Compared to other non-destructive testing methods, the (active) thermography offers some significant advantages, such as contactless, user friendly and fast material evaluation. Combining these factors, active thermography is highly suitable for industrial usage in material development and quality control.