Havarah and Kibuy - Lighting and Extinguishing a Fire
Havarah - Lighting a Fire
Definition
People do not naturally avoid flames on Shabbat: Pesachim 11a
Lighting a fire as one of the "Father" forms of forbidden melachah, or standing on its own: Shabbat 70a; Pesachim 5a-b; Keritot 20a-b
Lighting a fire perhaps having a punishment of a sin offering only, and not Divine Ex-Communication or Death, even if done intentionally: Shabbat 70a, 153b