Header and Footer on slides

To add or change a header and/or footer in your presentation, follow the next steps:

   1.   On the Insert tab, in the Text group, click Header & Footer or Date & Time or Slide Number:

   2.   In the Header and Footer dialog box, on the Slide tab, select the checkboxes for each of the three elements that you want to use:

You can set Date and time either to Update automatically or to Fixed:

• Update automatically pulls the current date from the computer's clock and formats it in whatever format you choose from the drop-down list. You can also select a language and a Calendar type (although this is probably not an issue unless you are presenting in some other country than the one for which your version of PowerPoint was developed).
• Fixed prints whatever you enter in the Fixed text box. When Fixed is enabled, it defaults to today's date in the mm/dd/yyyy format.

See also this tip in French: Affichage de la date, du numéro de diapositive et du pied de page sur les diapositives.