Browser caching can help you by storing some of the resources files locally at user’s browser. When they visit first time, it will take the same amount of time to render the page. However, when they will revisit that webpage or any other webpage on your website, refresh the page, they already have some of the files they need locally. This will results in decreased page load times.
To leverage your browser’s caching generally means that you specify how long browsers should keep images, CSS, and JavaScript files stored locally.
Mead complete guide here: http://wppaid.com/leverage-browser-cache-wordpress-blog/
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