Alignment refers to your team. Players on a mafia team are "mafia aligned" and players in the town are "town aligned".
A bandwagon is a collection of votes for a particular player. Often games will require a certain number of votes to be cast for a player before they are lynched, so other players will vote for them, joining the bandwagon. The first player to vote for someone starts that player's bandwagon.
This is the process of trying to make another player like you. Mafia will often try to employ this strategy with town players to improve how they are seen. Town players may try it as well to attempt to form a solid town contingent.
Bussing is a strategy in which mafia players actively try to get one of their teammates lynched. This can make those mafia players seem more like town since they were instrumental in getting a mafia killed. The term originates from "throwing someone under the bus".
To claim is to say you are a certain role. Claims can be faked by both town and mafia, for various reasons, or may be partially or completely true. Players under pressure of being lynched will often claim. The effectiveness of a claim depends partially on whether the setup is known. Claiming is disallowed in some games.
When one player claims, another may counterclaim, stating they are actually that role. This can be faked, just like a claim can be faked.
Day is traditionally when everyone talks and may lynch a player. It typically falls in between periods of night. In some games, mafia cannot talk during this period.
Flavor refers to a themed game. Many mods at Tar Valon put flavor in their game to make it more appealing.
A hammer occurs when there is a vote threshold in play, which, once reached, ends the day phase. A hammered individual is lynched once hammer is reached. Typically, hammering occurs when over half the existing voters cast a vote to lynch a player. Hammering is optional and only present in some games.
A hydra consists of two players playing the same role, at the same time. This may be allowed by a mod when there are two players who wish to play but who cannot fully commit to being dedicated 100% to the game.
Iso is short for "isolate". This is typically used when looking at just one player's posts to see if trends can be picked up on. It is rarely used at the beginning of the game but can be a common practice later.
L-1 is typically used in hammer games, and refers to when a player has accumulated one less than the number of votes needed to hammer them. It stands for lynch minus one.
To lurk is to be alive in game but not post. This can be frowned upon but is a legitimate strategy. A "lurker" is often described as someone who is not posting much, if at all.
In most games, the collective players may choose to lynch another player during the day phase. Sometimes this takes a majority, sometimes it goes to whomever has the most votes. Some mods will allow for a no-lynch to occur. A lynched player dies at the end of the day. Both mafia and town may vote in the lynching process.
Night is traditionally when the mafia plots to kill their targets. It typically falls in between periods of day. In some games, the town cannot talk during this period.