whether to change urls - pros and cons

[mike2010]

the best practice is not to change existing urls at all.

I know for a fact that people from Google said its a good thing to change the URL extensions to be more SEO friendly.

They had some conference and it involved vbSEO . (vbulletin's SEO mod )

[steveb]

He meant to build sites that had well structured URLs from the beginning.

If you have some crappy URL structure now, go ahead and change it to make it more friendly and useful for the next decade.

[g1smd]

If you change URLs, that means you change all the links in your pages to refer to the new URLs to.

You also need to set up a series of 301 redirects such that anytime anyone asks for an old URL they are redirected to the new URL. Failure to do that will cause untold grief.