Mods - what are they?
Many people want something slightly different to that which TNG provides. It's fairly easy to adapt the code to do what you want and many users have done this. Once a good idea is seen, others in the community want it and so the idea of a mod becomes established. It's fairly simple: a mod is a set of changes to the code of a particular version of TNG that makes it do something different.
As of version 8, TNG provides a Mod Manager which provides a simple way to distribute and apply mods. A mod consists of a file (which ends with a .cfg suffix) which lists the changes that need to be made in each module. This is placed in the mods folder. If extra php files are needed, these are included in a subfolder of the mods folder with the name of the mod.
When you select the mod manager on the Administration page it displays a list of the mods that have been uploaded and on the right is a button which either says Install or Delete. When you click the Install button it will make the changes and report on the success or failure of the operation.
If you don't like the effect of the mod you can simply return to the mod manager at any time and click the Delete button and the mods will be removed.
Mods are different from templates, which change the overall look and feel of the TNG system, and are another way of customizing the system to your needs.
New Versions of TNG
Popular mods have often been incorporated into a new version of TNG and therefore disappear as mods. Those that aren't, need to be changed to work with the new version.
Before applying any upgrade it's necessary to deactivate all mods and then reactivate those that are still needed after the upgrade. Very often a new version of the mod is required for a major update of TNG and if upgrading you may need to check the wiki such as this page for TNG V10. Since most mods are provided by users, time is given for users before major releases to make any changes that are necessary.
It is obviously possible for two different modules to change the same piece of code and this leads to a clash. It's also possible that two mods may change the system in incompatible ways even though different parts of the code are changed. There's no infallible way of detecting this in advance and when known clashes are documented for each mod and also in this wiki.
If you suspect a clash, please inform the maintainers immediately after checking the documentation. It is not possible for them to experiment with all possible combinations of mods and to always spot the problems. Normally there will be a way to contact the maintainer in the box on the right hand side on the wiki page for that mod.