A spacer image (also known as a spacer GIF) is a transparent image thats used to control spacing in autostretch tables. A spacer image consists of a single-pixel transparent GIF image, stretched out to be a specified number of pixels wide. A browser cant draw a table column narrower than the widest image contained in a cell in that column, so placing a spacer image in a table column requires browsers to keep the column at least as wide as the image.
Dreamweaver automatically adds spacer images when you set a column to autostretch, unless you specify that no spacer image should be used. You can manually insert and remove spacer images in each column if you prefer. Columns that contain spacer images have a double bar where the column width appears.
You can manually insert and remove spacer images in specific columns or remove all spacer images in the page.