Two families of dining rules exist worldwide, and knowing both keeps you safe. The universal set: wait for the host or eldest to begin, accept at least a taste of what is offered, keep phones off the table, pace yourself with the group, compliment the cooking, and thank the host warmly. Refusing dishes outright, rushing, or visibly disliking food are the impolite constants everywhere.
The local set is where preparation pays. Chopstick cultures forbid planting chopsticks upright in rice or passing food between chopsticks, both funeral echoes; rest them on the holder. Hand-eating cultures across South Asia, the Middle East, Ethiopia, and elsewhere use the right hand only, and often just the fingertips. Slurping noodles is appreciation in Japan and rude in Europe. A cleaned plate pleases some hosts and tells others they under-fed you, so watch what locals leave. Some cultures serve communally, where you take from shared dishes with serving spoons and never rummage for the best piece; others plate individually. Alcohol rituals, such as pouring for others and never for yourself in parts of East Asia, have their own etiquette.
In restaurants, add local tipping norms and who-pays customs. The reliable strategy at any table: start slowly, watch your hosts, and mirror them; imitation reads as respect.