The intent of this success criterion is to have content authors place instructions or labels that identify the controls in a form so that users know what input data is expected. Instructions or labels may also specify data formats for fields especially if they are out of the customary formats or if there are specific rules for correct input. Content authors may also choose to make such instructions available to users only when the individual control has focus especially when instructions are long and verbose.
The intent of this Success Criterion is not to clutter the page with unnecessary information but to provide important cues and instructions that will benefit people with disabilities. Too much information or instruction can be just as much of a hindrance as too little. The goal is to make certain that enough information is provided for the user to accomplish the task without undue confusion or navigation.
When labels are provided for input objects, the input object's relationship to the label (or to redundant text serving as the label) must be programmatically determinable or available in text per 1.3.1: Info and Relationships.
Providing descriptive labels AND one of the following:
The techniques at the end of the above list should be considered "last resort" and only used when the other techniques cannot be applied to the page. The earlier techniques are preferred because they increase accessibility to a wider user group.