If you heard of pdfLaTeX and do not know whether you should use it instead of 'normal' LaTeX, here is your answer. (Well, at least some clues to find your personal answer yourself.)
Han The Thanh wrote the pdf(La)TeX program to create file in the Adobe pdf (portable document format) files directly instead of using the long chain latex -> dvips -> pstopdf.
Pdf(La)TeX is an extention of (La)TeX; just like (La)TeX, it can work with or without LaTeX macros, i.e. plain (pdf)TeX only. I will use the term pdfTeX in the rest of this page to simplify notation; this stand for both pdfTeX and pdfLaTeX.
Basically, pdftex is fully compatible with standard LaTeX (exceptions: see below), but offers some nice extra features. I personally use pdfLaTeX only and I can only recommend to do so, unless you absolutely need something which lies in the 0.5% incompatibility range...
Pros:The most important one: you get pdf directly, and pdf files are platform (operating system) independent and require only a free program (Acrobat Reader) to view or print out. These two points are not met when someone send you a *.doc file... Oh, I hate these people... ;-)
pdfTeX can be configured to produce normal dvi output instead of pdf. You lose nothing when using pdfTeX!
Character protruding is supported. This means that characters do not end on a straight line at the right edge of the text, but can be shifted toward the margin depending on their 'optical weight' (in simple words: blackness). For instance, hyphens are usually shifted to the margin.
This technique was used in the middle ages already because artist and typographers discovered it to look more pleasing to the human eye. It was widely forgotton in the age of computer typesetting, but remember: normal people know nothing about typography (ok, you not, if you are are TeX user :-)), but still everyone knows quite well, whether a special text 'looks good' and whether reading it is easy and pleasing or not. You should definitely comply to the rules that typographers, printers and other professionals found out during centuries!
I really like character protruding. Most people say the text looks nice, but hardly anyone discovers what is different from usual computer written texts, even if you reveal that something special is used, something they probably have not seen before... :-) That's how typography works! Make reading your texts pleasant and enjoyable!
More graphic formats are supported (e.g. pdf and png)
You set several page transition styles (only useful for presentations).
You can set pdf-specific document info (author, copyright notes, ...) directly
PostScript (PS) is no intermediate format anymore; pdfTeX goes the direct way to pdf. In principle, this is an advantage, but some packages rely on modifying PS code. These packages, most notably psfrag, will obviously not work together with pdfTeX. Some people might call this the biggest drawback of pdfTeX, but is psfrag really a basic feature or rather the exploitation of a common workaround? Nevertheless: if you really need psfrag, then forget about pdfTeX. Knock-out criterion. Nothing comparable available for pdfTeX.
Pictures in the EPS (encapsulated PostScript) format are not compatible with pdfTeX. This sound like a big disadvantage, but in fact it is no problem at all. pdfTeX supports a lot of graphic formats, among them pdf itself. A program called epstopdf it provided with your (pdf)LaTeX distribution. This program converts eps to pdf files (which usually shrinks down file sizes considerably). You only need ghostscript installed to run it. The (non-free) alternative is using the full Acrobat package (which is more than the free Acrobat Reader).
Note: my boss still wants to use LaTeX. It is possible to write *.tex files that run with both pdfLaTeX and LaTeX. For our lecture notes, I wrote the following code segment:
\ifx\pdfoutput\undefined
\documentclass[german,dvips,a4paper,11pt,landscape]{report}
\else
\documentclass[german,pdftex,a4paper,11pt,landscape]{report}
\fi
The optional arguments 'dvips' or 'pdftex' are provided as global options to the \documentclass command. Therefore, hyperref, graphicx or other packages that need specification of a graphics driver always take the correct option.
The pdfLaTeX home page (and further links, e.g. to Adobe's pdf specifications) can be found here.