Currency refers to how recent the information is.
Ask yourself these questions when thinking about the currency of a source and its information:
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Sometimes, the currency of the source is very important. For example, if you are researching about a time-sensitive topic such as a current event, then it's important to find sources that have been published recently. Likewise, if you are searching for information about what restaurant to go to tonight, it's important to use current information. (You don't want to arrive at a location only to find that the restaurant went out of business ages ago!)
For example, if you are searching for literary criticism about Shakespeare's plays, then the currency might not matter at all. Criticism written in 1902 about imagery in Hamlet can still be relevant today.
(Thank you to Tacoma Community College https://tacomacc.libguides.com/c.php?g=373171&p=2523048)