This manual addresses the linguistic issues that arise in connection with annotating texts by part of speech ("tagging"). Section 2 is an alphabetical list of the parts of speech encoded in the annotation systems of the Penn Treebank Project, along with their corresponding abbreviations ("tags") and some information concerning their definition. This section allows you to find an unfamiliar tag by looking up a familiar part of speech. Section 3 recapitulates the information in Section 2, but this time the information is alphabetically ordered by tags. This is the section to consult in order to find out what an unfamiliar tag means. Since the parts of speech are probably familiar to you from high school English, you should have little difficulty in assimilating the tags themselves. However, it is often quite difficult to decide which tag is appropriate in a particular context. The two sections 4 and 5 therefore include examples and guidelines on how to tag problematic cases. If you are uncertain about whether a given tag is correct or not, refer to these sections in order to ensure a consistently annotated text. Section 4 discusses parts of speech that are easily confused and gives guidelines on how to tag such cases, while Section 5 contains an alphabetical list of specific problematic words and collocations. Finally, Section 6 discusses some general tagging conventions. One general rule, however, is so important that we state it here. Many texts are not models of good prose, and some contain outright errors and slips of the pen. Do not be tempted to correct a tag to what it would be if the text were correct; rather, it is the incorrect word that should be tagged correctly.