Free-to-play

Free-to-Play, F2P and several other variations are all used to describe non-members, playing the free version of Runescape

Disadvantages

 * A smaller world, without access to some specilist item shops and guilds.
 * Fewer servers
 * Limited number of quests
 * Most skills are limited in some way, others are unavailable
 * The Mage and Ranger are most seriously hampered, being unable to craft higher level runes or fletch their own arrows, while the Warior loses out on the top level of armor and weapons

Advantages

 * Some may not be able to pay - younger players may not have the means to
 * Even those intending to become members can build their levels up first, or see if it's really for them
 * Some people may choose to be members for a short time, after building up supplies that they can make arrows or high level runes from, and then go back to a bit of free player killing