XLIFF is important because managing bitext is the core process in localization. XLIFF keeps source and target aligned throughout all transformations in the roundtrip through the localization process, which should be standards-based, not proprietary.
Translation Memory Exchange. An XML-based standard that facilitates the exchange of data between different translation memory (TM) tools.
Why is it important?
The capability of moving data between different tools makes TMX important to the industry. However, its flexibility can limit its applicability, because tool vendors often create variants, which can hinder interoperability.