In layout you design your entire site once, using common HTML code.
The only difference to a html page is that you use placeholders where later the program inserts
the menu and content of the pages.
The structure of the layout is as follows:
<html>
<head>
<title>§title§ - §caption§</title>
</head>
<body>
<div style="float: left;
§menu§
</div>
<div style="width: 70%;">
§content§
</div>
</body>
</html>
In addition, the whole layout of your pages is defined in layout.
For every page you only need to enter the content (text, pictures, etc.).
The layout can be saved and loaded independent of the pages. And you can
temporarily show the pages with a different layout. So it's fast and easy to see
how the pages look in another layout to decide what look is best.
There are some
layouts for download
that you can use for your own projects.