Broken links are links which does not have valid target page.The page to which link is made does not exist.Broken links are bad for search engine optimization and you should always try not to have any broken link on your website.
This is very simple to say but is very difficult to maintain.A page to which you are making link to may not exist in future.So webmasters should check their website for presence of broken links periodically.This is part of SEO exercise and must be taken seriously.
This task is very troublesome if carried out manually.So I will introduce you to Broken links checker plugin which makes this task very easy (assuming you are using WordPress as your CMS).
This plugin checks your entire posts and creates a report of broken links,redirected links and normal links.This plugin does take time for analysis so it is better to run it during less traffic time to minimize server load.
You can keep it installed on your website and run it after a period but I would suggest otherwise.This is resource intensive task and there is no need to keep it installed and activated and check your website every alternate days.
It is better to deactivate it and if possible remove it from your website.You can install and run it once every month or 15 days depending upon your requirement ( number of new posts published , resource limit and any other parameter applicable in your case).
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