RAK - Random Act of Kindness
(from my understanding, this is when scrapping bloggers wants to share and giveaway from kindness to others. The items known as "blog candy" usually consists of goodies from their own stash. Sometimes, RAKs are given in a form of prize for Challenges, organised by groups of scrappers such as Scrap-It-Lah, or a random draw from the list of fans and friends who comments on their blogpost.
Acid Free
Acid Free papers are usually used for archival projects such scrapbooking or crafting purposes.
The reason behind using acid free paper is because it doesn't turn yellow or deteriorate as fast as non acid free papers.
Sketches
I never really figured out what this was until i started reading scrapbooking magazines.
I found out that it's actually a drawn layout "guideline" done by some designers which specifies the placing of the photos, journal, shapes and etc... Some challenges are based on sketches and it's amazing to see different scrappers coming out with different interpretation of the design that brings out the individuality of each layout although the placing is similar... :D
I'm no expert in this at all... :) maybe i'm wrong with the terms.
There's plenty more but i think i will stop here.