Interactions with others
Travian offers you the possibility to interact with your fellow players in three different ways:
Attacks
You have the possibility to attack each of the other players as long as he is neither in the beginner protection nor banned for e.g. inactivity.
In order to attack someone you need troops and a target. A target can be choosen via the map, the statistics or by entering the information of the village you want to attack via the rally point. The difference between a normal attack and a raid is the fact that a normal battle will be fought until one of the hosts is dead, raids will only do partial damage to both parties and in almost every case the attacker will have at least 1 surviving soldier.
Reinforcements
You have the possibility to reinforce each of the other players as long as the account is neither in the beginner protection nor banned for e.g. inactivity. In order to reinforce someone you need troops and a target. A target can be choosen via the map, the statistics or by entering the information of the village you want to attack via the rally point. Troops that have been sent to reinforce another village will stay there until they die in battle, you withdraw them or the owner sends them back. Their upkeep has to be paid by the village-owner.
Trades
The marketplace (prerequisites: Main building level 3 [in T3 additionally Granary level 1, Warehouse level 1]) offers you the possibility to send resources to other players as long as there are any in the current village. You can choose between accepting an existing offer, creating an offer yourself or simply sending resources to another village (mind the resource transfer rules!). In order to receive resources you do not need a marketplace but you are unable to see whether you receive resources without having a marketplace.
Messages
Via the right message-symbol you can read, write and, if you have Plus, archive ingame messages (IGMs) and manage your notes. Just enter the nickname of another player as recipient, a topic and the content of the message (mind the game rules!). Afterwards just click "send" and the message will be send to the other player. If you have the right to do so you can even send messages to your whole alliance with simply entering [ally] as recipient (not [your-alliance-tag]).