The ODT format is part of the Open Document for Office Application Standard, also known as OpenDocument. Originally developed by Sun Microsystems and based on XML, the standard has been defined and developed by the Organization for the Advancement of Structured Information Standards (OASIS).
OpenDocument is the native format of OpenOffice.Org Suite. Odt is the default version of the word processor OpenOffice.Org Writer.
Most often resolving problems with opening ODT files is very simple. Just install an appropriate program that supports such files. All of the listed programs support ODT files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of ODT files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate ODT files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the OpenOffice.org applications is not on the list, select "Browse" option in order to manually locate the directory where OpenOffice.org has been installed.
Sometimes problems with opening ODT files may not lie with the application itself, but can arise due to other causes, such as: