A summary of the entry.
If this contains HTML or XHTML, it is sanitized by default.
If this contains HTML or XHTML, certain (X)HTML elements within this value may contain relative URIs. If so, they are resolved according to a set of rules.
Some publishing systems auto-generate this value from the first few words or first paragraph of the entry. Other publishing systems misuse it to include the full content. In the latter cases, Universal Feed Parser ought to detect it and put the value in entries[i].content instead, but it doesn’t.
Some feeds include both a summary and description element for each entry. In this case, the first element will be available in entry['summary'] and the second will be available in entry['content'].