There are three parts to Xenia.
- The host respects the guest. A host must be hospitable to their guest and provide food, drink and a bath, if needed. It's impolite to ask questions until the guest's needs have been met.
- The guest respects the host. The guest must be courteous and must not be a burden.
- The parting gift (called xenion) is given to the guest to show the host's honor at receiving the guest
Xenia also included the protection of bards. In exchange for news and entertainment, they received a place to sleep, food, drink, and xenion. These bards were believed to be protected by Zeus, and any violator would be at the mercy of Zeus, or whoever he sent in his place.
An example of a violator of Xenia is Paris of Troy. While visiting Menelaus, king of Mycenaean Sparta, Paris kidnapped Menelaus' wife Helen. In response, Menelaus declared war on Troy.
An example of someone obeying Xenia occurs in the Bible. Lot, who was living in Sodom, allowed two angels to enter his home. He offered to wash their feet, and to give them food. When a mob came to his door, he offered his own daughters instead of his guests (I know this is unthinkable now, but it was the way Xenia worked then. Guests were more important than family).
I believe that this should be followed today. People should offer food and drink to guests (and most still do). Guests should treat the property of the host with respect, and should treat everyone in the hosts' family with respect. Anything farther should fall within the customs and laws of the society the host and guest are part of.