Excerpt « WordPress Codex

The Excerpt has two main uses:

  1. It replaces the full content in RSS feeds when the option to display summaries is selected in Dashboard › Settings › Reading.
  2. Depending on the WordPress theme, it can be displayed in places where quick summaries are preferable to full content:
  • Search results
  • Tag archives
  • Category archives
  • Monthly archives
  • Author archives

Source: Excerpt « WordPress Codex