Even if flash is very used on web pages a lot of web developers still don't know a correct way to insert a .swf movie into a website. There are different ways for different browsers, the <object> element with it's attributes is used for Internet Explorer needs, instead other browsers (like Firefox for example) recognize only the <embed> element. The problem is that this element isn't listed in HTML or XHTML specifications, soo the code is not valid.
To solve this problem I'm using this code which is working in both most important browsers Internet Explorer and Firefox:

PLAIN TEXT
HTML:
  1. <object data="path_to_flash" type="application/x-shockwave-flash" width="557" height="127">
  2. <param name="MOVIE" value="path_to_flash">
  3. </param></object>

Using this method, now you can easily insert flash content in your site without concerning that the final source will not be valid, this works fine for HTML and even XHTML 1.0 Strict .