What you need to know

input language
in our case, TEI P5
XSLT
XSLT 2.0, icluding XPath 2.0; we will pretty much ignore the existence of XSLT 1.0 or 3.0
output language
most commonly XHTML or TEI, but could be most anything (SVG, XSL-FO, DocBook, KML, METS, MODS, RDF, EAD, EAC, BiblioML, etc., or a home-grown or proprietary XML language; or plain text output like tab-delimited)

In addition, raw (X)HTML typically looks awful; you’ll need CSS to make the output look good in a browser

XSLT: where does it fit in?, slide 5 of 6