Any editor worth its salt has some provision for text snippet expansion. TextMate, Vim, and Sublime Text 2 all have this capability and Emacs is certainly no exception. If you're not familiar with the concept of snippets, the basic idea involves defining a keyword, which when followed with some trigger (keyboard shortcut or menu option), replaces that keyword with some predefined text. This functionality is a great boost to productivity as it prevents the developer from having to manually type potentially hundreds or thousands of lines of relatively boilerplate code.
As a developer, I tend to prefer automation whenever possible. Hours of your life are lost in the minutes spent doing that which could easily be scripted. The classic rule of thumb I try to follow is "if you have to do it twice, automate it."
A few months ago, I started playing around with Emacs. For roughly six years prior to that, I was a die-hard Vim fan. Vim will always hold a special place in my heart, but I have grown to love Emacs. I'll undoubtedly cover Emacs in more detail, but I'll leave that for other posts.
Undoubtedly, your grade school grammar teacher has scolded you at one point or another for your inadvertent use of a double negative. Statements such as “I don’t know nothing about physics”, while grammatically incorrect, are often semantically inaccurate as well. While the previous statement would commonly be understood to mean the person posses no knowledge of physics, the actual statement implies the opposite, that the preposition “I know nothing about physics” is incorrect. Certainly your teacher offered sound advice and one would be wise to heed such instruction.