Sonic screwdriver

The sonic screwdriver, also called a sonic probe or simply the sonic, was a highly versatile tool used by many people throughout the universe, the most prominent of them being the Doctor. They 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 objects and fry circuitry. 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 by frying their internal mechanics and causing the weapons to burst into flames and spark from the inside. The tool seemed to have electromagnetic properties and abilities, as it could be used to electrify the nervous system, and could create powerful frequencies and signals, as well as use sound to carry out its functions, even to the point where three of its latest incarnations where able to create a sonic force blast powerful enough to repel and destroy a Dalek while working together, as well as shoot green sonic energy waves to briefly incapacitate or stun a target.

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. (TV: The Day of the Doctor)

While almost always referred to as a sonic screwdriver, it has on occasion been referred to as a sonic probe by people other than the Doctor, such as Dalek Sec and a version of Amy Pond who had been stuck on Apalapucia for 36 years. The Tenth Doctor openly disliked this, and corrected those who did so. (TV: Doomsday, The Girl Who Waited)

Technology and functions
The sonic screwdriver was considered to be very advanced Gallifreyan technology. (PROSE: Heart of TARDIS)

The Doctor claimed that he either invented or designed the specific sonic screwdriver which he owned. When Kazran Sardick was confused as to what to do when it looked like Abigail Pettigrew was about to kiss him, the Eleventh Doctor told Kazran to trust him and kiss Abigail, as "It's this, or go to your room and design a new kind of screwdriver. Don't make my mistakes. Now, go." (TV: A Christmas Carol) When Captain Jack Harkness asked the Ninth Doctor, "Who looks at a screwdriver and thinks 'Ooh, this could be a little more sonic'?", the Ninth Doctor defensively responded, "What? You never been bored? Never had a long night? Never had a lot of cabinets to put up?" (TV: The Doctor Dances)

Other individuals had similar devices, such as the sonic pen used by Miss Foster (TV: Partners in Crime) and the sonic blaster used first by Captain Jack Harkness (TV: The Empty Child / The Doctor Dances) and later River Song. (TV: Silence in the Library / Forest of the Dead) Sarah Jane Smith had her sonic lipstick, (TV: Invasion of the Bane, et al.) and the Doctor himself once used a sonic cane. (TV: Let's Kill Hitler) Even Missy used a sonic umbrella. (TV: World Enough and Time/The Doctor Falls)

From time to time, the sonic screwdriver needed to be recharged. (TV: Silence in the Library / Forest of the Dead, PROSE: The Monsters Inside, COMIC: Bizarre Zero) It was self-repairing and could send out a homing signal to any parts that had been separated. (TV: A Christmas Carol)

Sonic screwdrivers and similar technology could not unlock a deadlock seal. (TV: School Reunion, The Night of the Doctor) However, Miss Foster's sonic pen could open the deadlock seals that it was programmed to within her own facility when the Doctor's screwdriver could not. (TV: Partners in Crime) It also couldn't unlock the doors to the TARDIS if they had been manually locked at the console. (TV: Utopia) Some or all versions were ineffective against wood. (TV: Night Terrors, The Doctor, the Widow and the Wardrobe, The Time of the Doctor, Empress of Mars) It didn't work in the presence of some models of hairdryers, although the Tenth Doctor stated he was working on it. (TV: Forest of the Dead, PROSE: Catastrophea)

The Doctor's screwdriver
The Doctor, throughout many of their lives, possessed a sonic screwdriver. They originally used a basic model in their first and second incarnations, before upgrading in their third. They continued to use this model until it was destroyed in their fifth by a Terileptil leader. It wasn't until they were in their seventh incarnation before they began to use a screwdriver again, taking on various different models throughout the years.

River's screwdriver
The Twelfth Doctor gave River Song's sonic screwdriver another screwdriver before River's final date with him at the Singing Towers of Darillium. (TV: The Husbands of River Song, Silence in the Library) This version of the sonic screwdriver somewhat resembled the Tenth Doctor's model when he met her at the Library, though it looked elaborately decorated and modified, featuring increased and enhanced functionality, including "dampers" and a "red setting" that allowed it to work without interference from the Doctor Moon. The Doctor gave it to River so she would be ready when she met his tenth incarnation in the Library. (TV: Forest of the Dead)

Other screwdrivers
Vastra had a sonic screwdriver that was a gift from the Doctor. She used it to shatter the glass of the Crystal Palace. It had a red tip, and was similar in design to that used by his eleventh incarnation. (COMIC: The Crystal Throne)

A clone of the Second Doctor also possessed a sonic screwdriver, which he used along with the Fourth Doctor's to send Hexford home. (AUDIO: Survivors in Space)

Romana II constructed her own sonic screwdriver. Her version was so impressive that the Doctor offered to swap sonic screwdrivers with her. (TV: The Horns of Nimon) Her version also included a silencer. (AUDIO: Luna Romana) She later gave it to the Doctor. (PROSE: Lungbarrow) Nonetheless, during the final term of her presidency, her third incarnation used a sonic screwdriver. (AUDIO: Intervention Earth)

Jackson Lake carried a primitive iteration of the sonic screwdriver. His version was a regular 19th century screwdriver, which he claimed was sonic by virtue of it making a sound when it was struck against a surface. (TV: The Next Doctor)

While trapped on Apalapucia for thirty-six years, Amy Pond cobbled together a sonic device from various pieces of technology, but insisted upon calling it a sonic probe. She later conceded that it was a "sonic screwdriver". (TV: The Girl Who Waited)

Behind the scenes
According to the non-fiction source REF: Doctor Who: The Visual Dictionary, which this wiki does not count as a valid source, a sonic screwdriver was a common and basic Time Lord device. If needed, a Time Lord could make one from scratch in very little time.