The Sonic Screwdriver — sometimes called the sonic — was a highly versatile tool used by The Doctor. He modified and ostensibly upgraded it over the years, giving it an increasing number of applications. Early versions were used mainly for the picking of locks and for projecting sound so as to, for example, detonate bombs. By the time of the Ninth Doctor, the sonic was able to also be used as a sophisticated scanning device, with medical applications. Subsequent incarnations gave it even wider functionality, such as the ability to hack into computers, provide geolocation and actively defend against some types of assault weapons.
All of these incarnations utilised the same software, though they used different cases. For all intents and purposes, the War Doctor's sonic was the same as the Eleventh Doctor's some 400 years later.