Where can I find documentation about TikZ/TikZPicture?

Question

When looking for different packages of creating timelines, I came across the following one:

\documentclass[12pt]{article}

\usepackage[a4paper]{geometry}
\usepackage{tikz}
\usetikzlibrary{snakes}

\begin{document}

\begin{tikzpicture}[snake=zigzag, line before snake = 5mm, line after snake = 5mm]
%draw horizontal line   
\draw (0,0) -- (2,0);
\draw[snake] (2,0) -- (4,0);
\draw (4,0) -- (5,0);
\draw[snake] (5,0) -- (7,0);

%draw vertical lines
\foreach \x in {0,1,2,4,5,7}
   \draw (\x cm,3pt) -- (\x cm,-3pt);

%draw nodes
\draw (0,0) node[below=3pt] {$ 0 $} node[above=3pt] {$   $};
\draw (1,0) node[below=3pt] {$ 1 $} node[above=3pt] {$ 10 $};
\draw (2,0) node[below=3pt] {$ 2 $} node[above=3pt] {$ 20 $};
\draw (3,0) node[below=3pt] {$  $} node[above=3pt] {$  $};
\draw (4,0) node[below=3pt] {$ 5 $} node[above=3pt] {$ 50 $};
\draw (5,0) node[below=3pt] {$ 6 $} node[above=3pt] {$ 60 $};
\draw (6,0) node[below=3pt] {$  $} node[above=3pt] {$  $};
\draw (7,0) node[below=3pt] {$ n $} node[above=3pt] {$ 10n $};
\end{tikzpicture}

\end{document}

When typesetting, we get this:

But although the code says \usepackage{tikz}, there is not a package with this name. According to the CTAN site, there is a macro package called pgf that «comes with a user-friendly syntax layer called TikZ.»

I have checked the pgf documentation, of course, but there doesn't seem to be a section related to the code I posted above. There are many options (some are very nice too), but nothing like what I'm searching. Am I missing something? I'd like to know what can I do beyond what that code offers (if there is something, of course).

Also: what is TikZPicture? Is this what I should be looking for? I'm quite confused at the moment.

Answer 1

1. pgf is a huge toolbox for graphics in TeX.

2. tikz is something built on top of that, with much user-friendlier syntax. Most people use tikz and not pgf; the manual for tikz (and pgf at the same time) is called pgfmanual, which might be confusing.

3. tikzpicture is a LaTeX environment defined by tikz.

The code you mentioned uses tikz; I'd recommend you to read chapters/sections 1 (basic ideas), 2 (the first tutorial, with examples of (among others) lines and nodes), 15.10 (decorations) and 56 (\foreach) of pgfmanual. Notice also that "snakes" were replaced by "decorations" in newer versions of tikz.

Answer 2

Since you have the TikZ/PGF relation in the comments and answers, here is another reason for the absence of a documentation. If you look at the definition file under PGF package you would see the following lines

\PackageWarning{pgf}{Snakes have been superseded by decorations. Use
the decoration libraries instead of the snakes library}

\usepgflibrary{decorations.pathmorphing,decorations.pathreplacing,decorations.shapes}

So that particular usage of snakes is now obsolete and replaced by the libraries given above. For a particular example of the difference between TikZ and pgf, please have a look at my previous answer here which shows two identical ways of higher and lower levels of drawing. I hope you appreciate that TikZ is pretty much easier to use since it uses a pretty fluent english command style.