For first-time offenders, blocks are typically no more than one month.
However, continued rule-breaking can lead to longer ban durations, even a year.
If you have been blocked twice already and still break wiki policies, you will most likely be infinitely blocked.
If you are under 13 years old, you will be banned until you turn 13. If someone doesn't explicitly state their age but implies that they are under 13, the default duration will be a year.
Appealing a block
If you want your ban to be lifted early, then you can ask the blocking administrator to appeal it.
There is no guideline for how you do this, but if your appeal is disrespectful in any manner, the admin most likely will not unblock you.
Go to Community Central and contact the blocking admin on their message wall there. Trying to appeal bans on any other wiki counts as cross-wiki stalking and will increase your duration. When taken to extremes, you can be perma-banned.
In your appeal message, you must explain why you believe you should be unbanned at the very least.
Do not continously message the admin. Message them once, and it can be considered.
Using another account to circumvent a ban placed on your account is abuse of multiple accounts, and will cause an infinite ban placed on the sockpuppet.