There are three different types of method in effector switching - True Bypass, Split Bypass, and Buffer Bypass.
This is a matter of how to handle signal when effecor is ON and OFF, which you have to know about for utilizing your gear 100%.
1. True Bypass
 True bypass sends input signal to output directly when effector is OFF.
60's Fuzz Face, Octavia, and Treble Booster are good examples of true bypass, and they output high impedance signals of 20 ~ 40 KΩ when they are either ON or OFF.
As true bypass connects input and output directly when it is OFF, the signal will flow well when the effector is OFF even in the absence of power supply.
But as illustrated above, mechanical noise(popping) is inevitable in switching action because it cuts and connects two points of circuit simultaneously.
Also it is a problem that the high impedance signal when the effector is OFF cannot overcome capacitance by cable length.

The myth :
"True bypass is the best way to preserve the original tone because it passes signal untouched when it's OFF"

This is NOT true.
Or, this can be true if you can keep the total cable length between guitar output jack and amp input jack under 18 ft (5.5 m), which is very inconvenient, impractical, or sometimes impossible.
Here is a very simple test. Prepare two identical cables of normal length(12, 15, or 18 ft), a true-bypass effector, a guitar, and an amp. Compare the sounds when you connected guitar directly to amp and when you put turned off true-bypass effector between two cables. You will notice obvious degradation of tone when the cable length is doubled. This is because true bypass cannot lower the signal impedance for fighting cable capacitance after it.

Another problem of modern true bypass effector is that it drops signal impedance level abruptly when it is turned ON, which results in two incompatible sounds - high Z when it's OFF and low Z when it's ON.
When you turn OFF a true bypass effector, the impedance is as high as that of a guitar output(20 ~ 40 KΩ) and you will set the amp tone control accordingly. Now you turn on the effector, then impedance drops down under 10 KΩ, which recovers the treble and punch lost by cable capacitance after the pedal when it's off and makes the tone much brighter - too bright, mostly. The situation will be a little better if the pedal had tone controls, but the inherent gap of impedance levels brings unavoidable heterogeneous tones.
This is not a big problem in 60's true bypass effectors like Fuzz, Octavia, and Treble Booster because they output similar high level impedance signals either when ON or OFF.

To get rid of the above problems in true bypass, a buffer bypass (line driver) effector needs be placed before or after true bypass pedals.
2. Split Bypass
Split bypass splits input signal to send one to effect circuit and the other to bypass. Most MXR® effectors are using this system.
There are no switching noise(popping), but a severe degradation occurs in bypass signal as it passes only a part of signal when it's OFF.
Also split bypass system cannot overcome cable capacitance after it.
You can fix this problem by putting a buffer before split bypass pedal so it can lower the signal impedance.
3. Buffer Bypass (Line Driver)
Buffer bypass system always sends signal through buffer(s) no matter it's ON or OFF.
Because buffer should be activated even when the pedal is OFF, the signal cannot pass through it without power supply even when the pedal is OFF.

As illustrated above, there can be just an input buffer or both input and output buffer by manufacturer's design.
Including Moollon® Buffer Age Series, also BOSS®, Pete Cornish®, and Ibanez® TS808/TS9 are using this system.
It is called "buffer" as it lessens or eliminates shock of abrupt impedance level change by keeping consistent impedance level, and also called "line driver" as it drives signal through long cables(lines) with low impedance.
Once a high Z(impedance) signal passes through a buffer, it changes into a low Z signal which is very insusceptible to noise and treble loss by cable capacitance so it can cope well with long cable connected after the buffer.
When used together with true bypass or split bypass, buffer settles the problems caused by these systems and makes tone much better and more flexible.

Note that a buffer should not be connected BEFORE some pedals like 60's Fuzz, Octavia, and Treble Booster which are supposed to operate with high Z input signals only, or they will sound very weird and uncomfortable because of the low Z input signals(Refer to Impedance - Example 3 for details).
Instead, connect buffer AFTER these pedals for more clear and punchy sound delivery to an amp.

Of course the buffer bypass system has shortcomings, too. - The buffer quality is very very important.
The buffer should not distort, amplify, or compress a signal at all. It should just lower the signal impedance without any tonal alteration. Buffers with even a very small defect connected in series can bring serious degradation of tone.

 The basic role of Moollon GW109S Buffer is to transmit guitar signal to amp or effector without any tonal alteration or signal amplification.
18 ft (5.5 m, the maximum allowable length of high impedance cable) and 6.5 ft (2 m, the minimum possible length for practical playing) cables were used as references for our research so the signal from a cable of the minimum length before a buffer and the signal from a cable of the maximum length after a buffer sould sound identical to each other.
Signal/Impedance Matching Circuit is the core technology of Moollon GW109S Buffer, which keeps the signal in 1:1 unity gain minimizing signal loss caused by cable capacitance and jack/plug contact resistance.