Ajax has it been invented to replace the Flash technology in the making of dynamic sites? Can we make Ajax applications as complete as with Flash?
Ajax can not always replace Flash, even if it can avoid the webmaster to use Flash in some occasions.
The inventor of the term Ajax said it, Ajax is more practical in some cases and in other cases, Flash is essential.
That in 2010, because in the near future, with the video and Canvas tags, HTML 5 will replace actually Flash, especially since it is supported by the major Web players, including Google.
When to use Ajax rather than Flash? When you want to achieve dynamic pages with text or bitmap images, not vector elements (which can be done with SVG, but which is not supported by all browsers).
Flash is an animation technology before it becomes a mode of interaction with the server and a tool for achieving user interfaces.
The video player allows to superimpose videos in pages and is supported by all browsers. This, as well as motion graphics, goes beyond what brings Ajax.
There are many games in Flash, some classics were also implemented on the platform.
All that Flash can make can also be made with HTML 5:
The advantage of HTML 5 is that it is an open format, standard and non-proprietary.