# A Question Regarding TikZ ellipse

When using `ellipse`

as a node shape, you need to load the `shapes.geometric`

tikz library.
You can do that by adding `\usetikzlibrary{shapes.geometric}`

in your preamble (usually immediately) after `\usepackage{tikz}`

.
Note that you don't need `shapes.geometric`

to draw an ellipse, only to use it as a node shape like in your example.
If you use several `shapes.xxx`

libraries, you can simply write `\usetikzlibrary{shapes}`

instead of listing them one by one.

As supplement to the Étienne answer:

- Tik Z & PGF Manual for Version 2.10-CVS is obsolete for years, I strongly recommend to use the recent version of the package as well as its manual.
- Actual version of TikZ manual is 3.1.5b (January 8, 2020), where your example is on page 141.
- Shapes Library is described in chapter
*72 Shape Library*starting at page 785, where in section*72 Shape Library*is stated:

In addition to the standard shapes rectangle, circle and coordinate, there exist a number of additional shapes defined in different shape libraries. Most of these shapes have been contributed by Mark Wibrow. In the present section, these shapes are described. Note that the library shapes is provided for compatibility only. Please include sublibraries like shapes.geometric or shapes.misc directly.

- Geometric shapes are described in section
*72.3 Geometric Shapes*on page 786. - For ellipse shape see pages 787 -- 788.