Stereo Recording

Whereas most of this  website is dedicated to on-stage and live mic and mixing techniques, quite often, a recording onto a simple, stereo 2-track is desired, to reproduce the original source as faithfully as possible.
Remember to use Cans to set-up recording mixes.

XY PAIR

Using two, identical cardioid microphones, positioned at 90 degrees to each other, with the capsules as close as possible. Each mic should 'point' towareds the edges of the stage/area to be recorded.
The combined axis is directed towards the source, with each mic collecting sound from sources directly in front of it, with central sounds arriving, in phase at each mic, combining and compensating for the off-axis loss when re-played. Having said this, the detail of central-sources may be lost, due, again, to off-axis response of the mics, but unlikely to be a problem unless mic angle is in excess of around 110 degrees.

ORTFE

System used on european broadcasts to compensate for the time-delay in sound arriving at the ears, the XY pair above are 100degree relative to each other and positioned exactly 170mm apart. (Office do Radiodiffusion Television Francais)

AB PAIR

Two mono, omnidirectional mics positioned several feet apart, parallel and facing source. One mic fed to each channel. The larger the distance between, the better stereo image, but too far appart and centre-detail may be lost.
The AB Pair can use Boundary Microphones if desired, this collects room-reverberation much better and works especially well with mics mounted on the back wall opposite a performance.

M and S PAIRS

Using two mics, one mono cardioid and a mono figure-eight. positioned close together (above), the cardioid points to centre-stage, as does the figure eight, so, the two 'lobes' of the figure eight extend to left and right.
OK?
Right, to get stereo from these two monos, you combine cardiod output with the '8' signal (first channel), and an out-of-phase '8' signal (2nd channel). You also have the option of adding a little of the original cardioid alone to the mix to aid clarity of centre-stage sounds.
Explaining why this works is complex, and if you can't figure out why this works, think harder. 

STEREO RECORDING

is a complex and highly-discussed artform, so for further info, look into the books / internet.