If you don't know yet, Runescape Classic is currently being developed by Jagex and has a new lease on life online. This November 2009, Jagex finally opened RS Classic to all members.
What is Runescape Classic?
This is the old version of Runescape. The current version of Runescape is sometimes called Runescape 2 (RS2) because it is the second version of Runescape. It is very old and neglected, with virtually no updates since RS2 was launched in 2003.
Previously, only veteran players who have been active in RSC have been able to play. RSC and RS2 were split off and are two entirely different games. So those players who had veteran status had two accounts - their regular RS2 account that everyone has and their RSC account. Experience and items are not shared between the two games. For example,if you level attack in RS2, you do not get the corresponding level in RSC.You would have to train attack in RSC to level it on your RSC account.
What about items?
When RS2 was launched, Jagex decided not to force people to start over from level 3. All their stats were copied and players retained all their stats from RSC when they started playing RS2. RSC accounts were not stat wiped either.
Players' banks were also copied but Jagex decided not to "duplicate" items. This is a somewhat irrational choice, IMHO, because the two games are entirely separate and cannot trade between each other. Many at the time of the launch speculated that this was Jagex's underhanded way of forcing people to play RS2 since they had nothing in their RSC banks.
After a while, due to public outcry, Jagex released a website feature which allowed people to transfer their items back to RSC. Note that this feature was available for a limited time only.
Veterans and Non-veterans
Back in 12-Jan-2006, Jagex announced that "only accounts which have played RS-classic at least once in the last 6 months (since it went members only on August 3rd 2005) will be able to do so from now on."
So if you didn't log in during that time, you couldn't log into the RSC servers. The players who did play during that time period are considered veteran RSC players.
This November 2009, RSC was opened to all members (for a period of two weeks), even non-veterans. Those who are interested in RS history can now take a look at what RS was like before 3D.