What is Phase?

WaveformsDaniel sent me the following question yesterday via the Ask Joe form. If you have a question, please ask! I’ll do my best to answer it either here on the blog or over in the forums.

Here’s Daniel’s question (which is a great one, by the way):

Okay, so in researching proper recording techniques I stumble upon the issue of “Phase” quite often. Most of what I’ve read deals with the electrical properties of phase / polarity. Most of which makes perfect sense, however, I have failed to see how this effects actual recordings. Enlighten me here, Joe. What practical knowledge do I need to know about phase when it comes to the recording process?

– Daniel