Image Placeholders

hie,

I have heard about something called Image Placeholders. What do you mean by Image Placeholders ? Is it a feature or an application ? Where or for what purpose it is used ?
Kindly provide some necessary information about the same.....
thanks

I have used Image Placeholders in Dreamweaver. Initially, in Dreamweaver, I had to wait for the graphics to be complete or put in my own versions of them in order to create a design. But with Dreamweaver placeholder images, it allows me to define the size and location of images in the design without worrying about what the images will be.

Image Placeholders
An image placeholder is a dummy image designed to draw attention to the need for an actual image.

An image placeholder is useful when you lay out web pages because it allows you to position an image on a page before you actually create the image.

To insert Image placeholder -

1. In the Document window, click once inside the first row of the first table.
   
   
2. Select Insert > Image Objects > Image Placeholder.
   
   
3. In the Image Placeholder dialog box, do the following:
   
   • Type banner_graphic in the Name text box.
   • Enter 700 in the Width text box.
   • Enter 90 in the Height text box.
   • Click the color box and select a color from the color picker. For this tutorial, select a reddish brown (#993300).
   • Leave the Alternate Text text box blank.
   
   
   
4. Click OK.
   
   The image placeholder appears inside the first table. The image placeholder displays a label and the size attributes of the image that you'll eventually place there.
   
   
5. Save your page.

You can also insert slightly more advanced image placeholders to control how your images are aligned by

The different modifiers are listed below -

***image1*** insert image with default alignment
***image1:left*** insert image left aligned
***image1:center*** insert image center aligned
***image1:right*** insert image right aligned
***image1:url*** insert image URL