Understanding the type of knots that are allowed to be opened on Shabbos.
Gathering Fruits Together Which Spilled Out of a Basket or Box Indoors (e.g., a House, etc.);
Bringing a Siddur or Machzor to Shul for After Shabbos. Bringing Wine or a Megila for After Shabbos;
Washing Off an Item That Has an Insect on It (e.g., Utensils, Fruits);