Don’t auto-populate form fields with text
Form input fields can be coded to contain text that appears by default in the text field. Designers often use this technique in place of a field label to supply information about the purpose of the field. For example, the default text search is common in a search field. Generally this technique is used to conserve screen real estate: a single search field and submit button takes up less space than a search label, search field, and submit button (Figure 9.7).
Figure 9.7: Field labels explain the purpose of a field to visual and nonvisual users. In order to conserve screen space, labels are often left off (1) or supplied using default field text (2), which can cause usability problems. The best approach is to use a text label (3) marked with the
LABEL FOR tag to explicitly bind label and field. www.medlineplus.gov, www.nps.gov, www.nlm.nih.gov
The best way, by far, to label form fields is to use a field label, as described above. Properly labeled fields work for all users and do not present usability challenges. Create designs that can accommodate the additional space required for field labels rather than using a workaround, such as default text.