It's easier to understand the terminology when you discover that nearly everything is based around Digital Audio Workstation applications like Studio One being patterned after a real, physical recording studio, where instead of everything being virtual (VSTi virtual instruments and VST effects plug-ins), it's actually physical devices.
Rollback the clock 100 years, and the magnetic tape machine was invented in Germany by Fritz Pfleumer and soon was used to record NAZI propaganda which was broadcast by NAZI radio stations to local radios provided in the strategy of the Volkswagen, where the radio sets were affordable and sufficiently good for receiving radio broadcasts. By the mid-1930's, the Germans had broadcast television, and the 1936 Olympics in Berlin was broadcast to a handful of local German televisions, also provided by the NAZI propaganda machine.
After the Second World War, the US military discovered the German magnetic tape machines and these soon were brought to America where the design was upgraded and modified to create Ampex magnetic tape machines, which Bing Crosby used to record his radio programs so they could be broadcast in different time zones. Bing Crosby gave two tape machines to Les Paul who then used them to create songs with multiple layers of guitar and Mary Ford's singing.
Historically, strange as it might be, it's accurate to suggest that "Sgt. Pepper's Lonely Hearts Club" (Beatles) was recorded using essentially the same technology that NAZI Minister of Propaganda Joseph Goebbels used to record audio programs to promote the NAZI Party.
External signal processors (proper terminology) are things like reverb units, guitar effects, compressor-limiters, and so forth; and in a real recording studio they are mounted in cabinets and shelves colloquially called "racks", where the photo shows one of the two racks I have here in the sound isolation studio, mostly for lead guitar.
The second photo shows what I call the major sections of the Studio One graphic user interface (GUI), where for reference what I call "track lanes" map to strips or vertical sections of magnetic tape in a physical magnetic tape machine, where by the late-1960's there were 8-track magnetic tape machines and perhaps 16-track magnetic tape machines where 1" magnetic tape for an 8-track tape machine would have a 1/8" section for each of the 8 tracks. This led to the visual concept for the track lanes in Studio One; and they work the same way but actually are easier to modify and splice where for example Butch Vig (producer for Nirvana and others, and drummer for Garbage) is skilled in slicing magnetic tape and then adding other audio in places of the tape which he removed with a razor blade.
It was common beginning sometime in the late-1950's to record a song but then to cut the magnetic tape into sections which could be spliced in different sequences where the original might be {verse, verse, chorus} but the producer wanted it to be {verse, chorus, verse} without needing to record everything a second time. The audio-engineer would cut the tape after the first verse; separate the second verse and chorus; and then splice them together to create {verse, chorus, verse}.
In Studio One, there is a Mixing Board which is patterned after a real physical mixing board in the recording studio; and each track has a volume slider, balance or panning control (not the same), inserts, sends, and other stuff, where the "Inserts" are like at tiny rack and generally cascade where for example if the first effect is reverb and the second effect is echo, then the reverb is input to the echo, so that the echo then has reverb, and vice-versa.
If you want to control each effect separately, then use something I call a "Custom Image" where instead of just one track there are several copies of the same audio but each copy is on a different Instrument Track or Audio Track and has its own effect. The "Custom Bass Image" has the same effects but the sources are different (Gibson EB-0, Monotone Bass Synth, and Cyclop), but the concept is the same--more than one thing, each able to be controlled separately and independently to create a custom image where one "instrument" actually is composed of several instruments,
I am not certain, but it sounds like the word "and" and a guitar phrase were spliced "Maybe:" (The Shangr-Las).
Perhaps the best example is "Strawberry Fields Forever" (Beatles), which is two versions spliced together, where one version was slower, so the tape machine had to be speeded-up, which was done with a variable-transformer similar to the way the engineers at Abbey Road Studios created a device using two tape machines for doing Automatic Double Tracking (ADT) which John Lennon requested since he did not like to sing the same thing over and over, where they key is to vary the speeds of the tape machines so there were small variations in the what actually was one vocal track.
