If you are on this website, most likely you have already spent time reading and researching the Norden Bombsight. Entire books have been written about it, and the two best are "The Legendary Norden Bombsight" by Alfred Pardini and "America's Pursuit of Precision Bombing, 1910-1945" by Richard P. Hallion. Don't believe everything in the Wikipedia article and only half of Gladwell's infamous TED talk.
World War I had resulted in enormous casualties fighting from the trenches over small pieces of territory, and between the wars the concept was developed that perhaps aircraft could fly over the battle lines and destroy the enemy's capacity to wage war. It was felt that this ultimately would result in fewer lost lives and a shorter conflict.
Carl Norden, a Dutch engineer, had worked for Elmer Sperry on his gyroscope initiatives. Dissatisfied with that position, he struck out on his own and began developing gyroscopically stabilized bombsights. Norden, for obscure reasons, intensely disliked the Army and would only deal with the Navy. Therefore, all of the Army Air Corps and USAAF bombsights had to be purchased through the Navy. This is why some bombsights have data plates showing them to belong to the Navy, and all Norden bombsights have an anchor stamped on the front. He developed a long line of bombsights culminating in the Mark XV as designated by the Navy, but more commonly known as the M-9 by the Army. Norden also had a an intense dislike of electronics, so his bombsights were purely mechanical, with racks, pinions, cables, and levers, but no tubes or resistors.
The "bombing problem" had been known for decades, and Norden's bombsight was one of several solutions. The United State used two other bombsights in World War II, the Sperry S-1 and the Estoppey D-8. However, the Norden proved superior in testing and was selected over the others as the primary bombsight. The Navy eventually abandoned level bombing in favor of dive bombing and torpedo bombers, leaving the Army Air Corps, and later, the USAAF, as the primary user of these bombsights. Around 90,000 Nordens, 9,000 Estoppeys, and 5,000 Sperrys were produced.
Norden partnered with Theodore Barth in his business enterprises, and two companies used their combined names. The first was the Barden Ball Bearing Company. Norden had a great difficulty in finding ball bearings that would meet the exacting standards required for his bombsights, and in frustration he and Barth decided that they would have to manufacture their own ball bearings, and thus created the company that shared parts of both of their names. In addition, as the demand for the bombsights increased, additional manufacturers were added and Norden and Barth created a second business in Indiana at a Bureau of Ordnance facility, and named that factory Lukas-Harold, after Norden and Barth's middle names. Therefore, a Lukas-Harold bombsight was made by a Norden company. There were three other manufacturers, Remington, the Victor Adding Machine Company, and Burroughs. These five manufacturers all had their initial on the sighthead as part of the serial number: N, L, R, V, or B.
Finally, it became clear that human pilots were not going to be able to hold the aircraft steady enough in turbulent combat conditions for the bombardier to adequately do his job. It was necessary to devise an autopilot for this purpose. Norden created the SBAE (Stabilized Bombing Approach Equipment) as designated by the Navy, or AFCE (Automatic Flight Control Equipment) as designated by the Army. However, this proved inadequate and the government commissioned Honeywell to develop the C-1 Autopilot, as Honeywell had experience in thermostats, which make extensive use of feedback circuits. The Norden and C-1 combination proved effective, although the latter did make use of electronics and there was an electronic interface with the bombsight.