I almost never see patterns sold with yarn or those online using the long forms of stitch and technique names.
Yes, most proper beginner tutorials almost always have a legend for this sort of thing but not always. The intermediate to advanced ones I would think expect you have learned this by now.
What are the common stitch and actions abbreviations that are found in patterns and what are the long forms of them? Are there any distinctions when it comes to US/UK?
There are about nine or ten main stitches that are the most commonly used and, of them, four or five are probably used the most.
These may be used on their own or in conjunction with the abbreviations above.
Also, many patterns use an asterisk (*) to mark a repeated section of work.
There are other terms that some sites may define like pc (popcorn) or cl (cluster) but these should be defined in your pattern because what each pattern considers a popcorn stitch or cluster will vary greatly. They are non-standard, so look for a section in the instructsion that breaks up these terms into their smaller parts for you.
