Research in some subjects require more current information than others, such as topics in the sciences or business. Researching topics in areas such as literary criticism, history, and music can make use of all information regardless of date. Criticism of Shirley Jackson's "The Lottery" from the 1970s will not be replaced as newer criticisms are published. On the other hand, information about effective HIV treatments will most definitely be replaced as newer findings are published.
As a rule, you should not assume that historical topics will be on the Web at all. Since the Web as we know it began around 1994, information about topics and events before then probably will not appear on the Web unless it is someone's personal interest. High interest topics, such as the holocaust, will be more likely to be covered by web pages than smaller issues or topics such as the photographer Llew E. Morgan.
In general, you should determine the date of the information posted on the Web page. Confounding this task is the fact that, when included, dates posted on web pages can have several meanings. For example, a date of October 10, 1999 could mean:
