The fields plugin allows you to add custom fields on glpi types : tickets, computers, users...
Directories "inc", "front" and "ajax" should be available in writing for apache user

Addionnal data can be added :

• In object tab
• In main form of object (above save button)
• In form of a tab (Warning, this feature is experimental)

Possible fields type are :

• Header (title bloc)
• Text (single line)
• Text (multiple lines)
• Number
• Dropdown (always a tree dropdown)
• Yes / No
• Date
• Date / Hour
• Glpi User list

There is a migration script from "customfields" plugin.
WARNING : this one is experimental and deserved to be more tested. We strongly advise you to backup your data before using it

Documentation

For 0.84 plugin : https://github.com/pluginsGLPI/fields/blob/0.84/bugfixes/documentation/doc_plugin_fields.asciidoc