ATW's and all waters downstream from ATW's: Stocked. Minimum size = 7". Limit is 5 from opening day till Sept. 2. From Sept. 3 through Feb. 28, the limit is 3. March 1 through the regional opening day is totally off limits to wetting any sort of line. Opening days are listed in the book and on the commission website, and start earlier in the SE portion of the state compared to the rest of the state.
Special regulation: There are a variety of special regulation streams, and they are listed individually. In all of them, I believe fishing is permitted year round. But size and creel limits vary, generally more restrictive than ATW's. Some are no harvest at all, while others have more restricted size limits or dates, etc. Also, some carry tackle restrictions (artificials only, or fly fishing only, etc.).
Class A: These are NOT stocked. They can also carry special regulations, in which case the special regs always take precedence. But assuming they don't have special regs, then from opening day through Sept. 2, the rules are the same as in an ATW. There is no extended season, so from Sept. 3 through opening day, you are allowed to fish but on a catch and release basis only, no harvest.
Not ATW, not class A: We've debated this on this forum before, as the fish commission literature is vague and sometimes somewhat contradictory. Opening day to Sept. 2 is the same as an ATW. The rule actually states that from Sept. 3 through opening day, you can not, even unintentionally, "harm" a trout. What that entails is up for debate, but the consensus here is that you can fish on a C&R basis, making the rules are pretty much the same as for class A streams. It seems that while not prohibited, they aren't exactly encouraging us to fish these between Sept. 3 and opening day.