Backgammon has a long cultural history as well as precise modern competition rules. Keep them separate: an old board does not prove unchanged modern rules, and a single browser game does not automatically constitute a tournament match.
In this guide
A dated historical object
The Metropolitan Museum holds a Small Shahnama folio made around 1300–1330 in Iran or Iraq, depicting Buzurjmihr explaining Nard. It provides historical cultural evidence, not a complete rulebook for our modern backgammon.
Further reading: The Met: Buzurjmihr explains Nard, ca. 1300–30
A game and a match are different
A match has an agreed target score. Singles, gammons and backgammons contribute to it, with a cube changing their value when used. Match score therefore affects risk decisions. Near the target, avoiding a large loss can matter more than maximizing the size of one win.
Further reading: UKBGF: An Introduction to Backgammon (2019)
Crawford: one game without the cube
Under the USBGF rules, the cube is unavailable for the first game after either player reaches one point short of winning the match. That is the Crawford game. If the match continues afterwards, cube use resumes. This restriction covers one specified game, not every remaining game.
Further reading: USBGF: Rules for In-Person Play
Competition habits without invented platform features
Before an event, check its published rules, target, time control and dispute procedure. Let the opponent see the complete move and distinguish rolling, moving and confirming. Our local timer is a time display, not a promised tournament clock. The site does not thereby provide a Crawford match or an official tournament.
For study, record your choice before using Help: race or contact, intended points and expected replies. Review the reasoning rather than just wins and losses. One game contains substantial dice variation; consistently reasoned choices are a more useful training objective than a supposed dice trick.