How to move a Wiki Space from one Confluence instance to another?

I have been asked many times by my colleagues about how to move a wiki space from one Confluence instance to another. So, here are the steps to do that:

• Export the desired wiki space to XML (since it includes everything i.e. attachments, comments etc.). For details, check http://confluence.atlassian.com/display/CONF32/Confluence+to+XML
• Once you get the exported ZIP file, next step is to restore that wiki space in the other Confluence instance where it needs to be imported. To restore the exported wiki space, check http://confluence.atlassian.com/display/CONF32/Restoring+a+Space 

What if the versions of source and destination Confluence instances don't match?

If the versions of Confluence in both instances don't match then first step is to know the Build Number of the Confluence where you want to restore the wiki space. You should check its Build Number (based on your Confluence version) from http://confluence.atlassian.com/display/DEVNET/Confluence+Build+Information. Once you know the build number, follow below steps:

• Unzip the exported ZIP file
• Open exportDescriptor.properties file
• Change buildNumber=XXX (where XXX is the build number for your destination confluence version)
• Save the file
• ZIP the files again and use this updated ZIP file to restore the wiki space. 

Atlassian doesn't guarantee about this approach but it's the ONLY solution and it has always worked for me.