Ideas, methods, and systems are not covered by copyright protection. According to the US Copyright Office, Circular 2, this covers quite a few things including:
Making, or building things
Scientific or technical methods or discoveries;
Business operations or procedures
Mathematical principles
Formulas, algorithms
Any other concept, process, or method of operation
Commonly Known Information is not covered by copyright protection. This category includes items that are considered common property and with no known authorship. This includes phrases such as “The sky is blue,” which have no known authorship associated with them.
Other examples include:
Standard calendars
Height and weight charts
Telephone directories
Tape measures and rulers
Lists or tables taken from public documents
Choreography is not covered by copyright protection. A choreographic work, whether original or not, is not subject to copyright protection unless it has been videotaped or notated.
The same applies to speeches that have not been transcribed before or after they are given, as well as any other types of performances.
Names, Titles, Short Phrases, or Expressions are not covered by copyright protection. That catchy slogan you came up with for your business? No dice on a trademark.
The good news is that while not protected by copyright, if it pertains to your business (for example, goods and services), it can be protected with a trademark.
Also exempt:
Names
Titles
Short phrases or expressions
Product descriptions
Pseudonyms
Titles of works
Business names
Recipes also fall under this category. Specifically the listing of ingredients (even if it's your own recipe ingredients) is not protected by copyright. This applies to formulas, compounds, and prescriptions as well.
There are exceptions however, such as when recipes are compiled in a cookbook. Or if the recipe is accompanied by “substantial literary expression," or a specific combination of recipes, there may be a basis for copyright protection.
Fashion (that is, a shirt, dress, or other article of clothing) is not protected by copyright law. Despite the fact that copyright law protects such things as architectural design works (Circular 41) or works of the visual arts (Circular 40), fashion is all about clothing and accessories, which under copyright law are considered “useful articles."
It is possible however, to copyright a specific fabric pattern (Burberry plaids for example), but not the actual dress.
And, it should be noted that while designs can't be copyrighted, they can be patented.