Cycle through a list of webpages every 30seconds (Update pages every 30mins??)

I am new to HTML code

What is the开发者_StackOverflow社区 code needed to store a number of different webpages and cycle through them every 30seconds? (The webpages need to be updated every 30mins)

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If a request every 30 seconds is going to take down your servers, it's time for a new server and/or application rewrite.