Overview
Run the pdfTeX typesetter on file[.tex], usually creating file.pdf. If the file argument has no extension, ".tex" will be appended to it. See tex(1) for details of command-line parsing.
pdfTeX is a descendant of TeX that can create pdf files directly as well as dvi files (determined by the value of the \pdfoutput primitive parameter). It includes the etex(1) extensions, and adds many more extensions of its own. In dvi mode, pdfTeX can be used as an upward-compatible replacement for the TeX engine.
The typical use of pdfTeX is with pregenerated TeX formats (.fmt files), usually with pdf output enabled. For example, the pdftex command uses the plain TeX format, and the pdflatex(1) command uses the LaTeX format. As described in etex(1), the e-TeX extensions are enabled when building the .fmt file.
Image formats supported
In pdf mode, pdfTeX can natively handle the pdf, jpg, jbig2, and png graphics formats. It cannot include PostScript or Encapsulated PostScript (eps) graphics files; you can convert them to pdf using, for example, epstopdf(1). The PostScript files output by mpost(1), which are highly restricted in their use of PostScript, can be handled directly using the supp-pdf.tex macros, or converted to pdf with mptopdf(1).
Program variants
Starting with version 1.40 (around 2007), pdfTeX incorporated the e-TeX extensions, and the pdfetex and etex executables became symlinks to the pdftex binary. The etex executable generates dvi files by default; pdfetex has the same behavior as pdftex.
Both engine and driver
When generating pdf output, pdfTeX must have all necessary font and device information and thus is acting like a device driver with dvi output, similar to, say, dvips(1). Therefore there are various primitives to specify the device information, such as the height, width, resolution, and so forth. Also, pdfTeX reads glyph information for the fonts used, e.g., from Type 1 or PK bitmap files. pdfTeX also supports TrueType fonts, but it's necessary to define an encoding before using them (see references). OpenType fonts are not supported.