In Arelith, each area has certain "flags". You see which flags are active whenever you enter a new area (they appear as words in square brackets (). Each has its own meaning, but the meanings are not readily apparant. This article should give you a better idea of what each flag means.
Off by default, [PvP] indicates that any players killed in this area will not immediately be sent to the Death area, but will get up on one hit point after a delay of 20 seconds. The normal death penalties do not apply, and experience is not gained for killing players' character. This is intended to be used in arena-type areas, where characters may face off against one another in a safe environment, in the knowledge that none of the attacks there are going to be lethal.
The [Rest] flag indicates that the area can be rested in comfortably. Designed primarily for inns and similar areas, [Rest] allows one to rest no matter what their tiredness state percentage is (normally one would have to be below 50% to rest). This is off by default.
The [Magic] flag indicates that the area contains the presence of the Weave. Mechanically, this means that spells can be cast in the area. Areas without the [Magic] flag are considered "dead" magic and are quite rare. This flag is on by default.
Every hour, a character is given bonus experience according to their Roleplaying Bonus, and their hunger, thirst and fatigue state values fall slightly. This only happens in areas with the [State] flag enabled: areas such as the entry area and the Death area do not have [State] enabled. The only in-character area with [State] disabled is Death; everywhere else hunger, thirst and fatigue act normally.
Portals are fairly common on Arelith, and the Portal Lens item allows one to teleport to a known portal at will. This can be done in all areas with the [Teleport] flag enabled; if it is disabled then teleporting is impossible. This also applies to the -teleport console command. It is enabled by default in most areas.
[Transfer] indicates that a character can lose his or her items. It is enabled in almost all areas; Death being a notable exception. If this flag is disabled, items cannot be transferred between players or dropped. In addition, trap kits cannot be set. This is enabled by default.
As opposed to [PvP], [Death] simply indicates that a character can be killed. If [Death] is disabled, all PCs in the area are immortal which means that they can be damaged but can never be killed. [Death] is enabled by default.
Many of these are simply common sense settings for various areas. However some, such as [Magic], can be dynamic. DMs have the ability to change any of these flags in any area at will, so if, for example, a DM-possessed mage was warding an area against further spellcasting in a scene, that can be achieved by simply switching [Magic] off.