Rules are interpreted at the table
Official rules provide the baseline. The DM applies them to messy situations, makes rulings when the exact case is unclear, and may record recurring rulings as house rules.
Volume One
Expert Topics
Nuanced questions, edge cases, terminology, and table variations.
Timing creates disputes
Surprise, readied actions, reactions, spell timing, stealth, and simultaneous choices can raise edge cases. A quick ruling may keep play moving, with a deeper check after the session.
Tables vary
Some tables use maps for every fight. Others use theater of the mind. Some allow broad source material. Others restrict options. The right answer is the one the table understands and agrees to use.
Edition labels matter
D&D has multiple editions and revisions. When character options or rules conflict, check which rules version the table is using before assuming a source applies.