It depends on the context. If it is about the specific web pages(that were defined before) then you should use definite article. She often visits the web pages in search of information needed for her study (For instance if she usually visits EnglishForward) And if you meant that she uses internet to search for the information so that she always visits different sites you should write: She often visits web pages in search of information needed for her study
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And if you meant that she uses internet to search for the information so that she always
She often visits the web pages in search of information needed for her study (For instance if she usually visits EnglishForward)