Comments start with: # and extend to the end of the Line
'Text Strings': can be enclosed in 'single' or "double" Quotes. 
Yaml has these Structures: 

 Sequence:

  - Sequences are simply ordered Lists of Yaml Structures (recursive!)
  - In Block Mode, each Item is on a single Line prefixed by a Dash '-' like this Line
  - In Flow Mode, several Items are placed in angular Brackets, separated by Commas or Tabs: 
     [Apples, Pears, Bananas, etc.] 
 Mapping: 
  - Mappings are a Set of unique Keys, each mapped to a single Yaml Structure (recursive!)
  - Keys can also be Yaml Structures (recursive!), but must be prefixed with a Question Mark '?' if longer than 1000 Characters
  - In Block Mode, each Pair is on a single Line with the Key separated by a Colon ':' from the Value
  - In Flow Mode, several Items are placed in angular Brackets, separated by Commas: 
     {Apples: Fruit, Spinach: Veggie, Salmon: Fish }

 Anchor and Reference:

  - &Anchor Anchors mark a Yaml Structure and must be unique within a Document 
  - References avoid repeating the above Data like here: 
     *Anchor

 Scalar:

  Text can be written in different Notations: 
   - In Block Mode, each Pair is on a single Line with the Key separated by a Colon ':' from the Value
   - In Flow Mode, several Items are placed in angular Brackets, separated by Commas: 
   - Double-Quoted Text can employ C-like Escape Sequences using Backslash '\': \r, \n, \t, \f, \v, \0, \\
   - Single-Quoted Text can contain any Character; single Quotes must be doubled though
  Numbers: 
   Numbers are supported in different Notations: 
   decimal: 3.1415926
   hex: [0x00, ..., 0xfff, ..., 0xAffe] 
   octal: 0o777
   .inf: Infinity; also -.inf for negative Infinity 
   .nan: Not a Number, results from e.g. 0/0, .inf / .inf or 0 * .inf
  null: is an empty Object
  Boolean: 
   - true
   - false

Number: 3.1415
Spaces or Tabs can be used to indent and nest Structures