An ODT file is a text document created with Writer, the Apache OpenOffice word processor. It contains different elements such as text, images, drawn objects, and styles. ODT files are formatted using the OASIS OpenDocument XML-based standard.
ODT file open in Apache OpenOffice Writer 4.1.3
Writer is one of several programs available in the OpenOffice suite. It is similar to the Word program available in the Microsoft Office suite. The ODT file is the main file used by Writer to save documents the same way that Word saves documents in the .DOCX file.
OpenDocument text files can be opened and edited with any OpenOffice-compatible program, including: NeoOffice (Mac), AbiWord (Mac & Windows), and KWord (Unix). They can also be imported into Google Docs, Google's web-based word processor included with Google Drive. ODT files can also be opened in Microsoft Word and saved as DOCX files.
NOTE: Apache OpenOffice was formerly known as OpenOffice.org.