The extensible markup language XML has become the de facto standard for information representation and interchange on the Internet. As XML becomes widespread it is critical for application developers to understand the operational and performance characteristics of XML processing. The processing of XML documents has been regarded as the performance bottleneck in most systems and applications. XML parsing is a core operation performed on an XML document for it to be accessed and manipulated. XML processing occurs in four stages: parsing, access, modification, and serialization. Parsing is an expensive operation that can degrade XML processing performance. This paper is a literature review of the various issues involved in XML parsing.