Etymology: Thor's Day.
What I use it for: Thor was the patron of the thralls in Norse society. Thus, on His day, I worship my own Patrons. This constantly causes problems with my rituals, however, since my Patrons are two very different Personages. Esus is a God of War, apparently akin to Odin, though it's hard to tell. Eris, however, is a Goddess of Chaos, and She has a very different idea of how ritual should go than Esus does. See my essay on Eris and ADF ritual for the details on larger rituals, but She seems okay with my devotional rituals on Thursdays. Maybe it's because I'm not really structured in the manner I do these daily rituals.
Importantly, I always hear back from my Patrons. They always speak to me when I open to Them. These rituals have been of paramount importance for learning about Esus, and They have taught me much. Sacrifices depend on what I need, but are often (again) grain, mead or beer.
Back to the Observances.