Ping allows a weblog to send an XLM-RPC signal to Ping Servers to tell their services that its content has been updated.

Pinging is a way for you to electronically let search engines and other websites know, that you have new or revised content on your website. The ping alerts websites like search engines, feed aggregators, social networks and subscribers, that there is updated content on your site.

Pinging is the technique use to inform or send an automatic notification to a search engine to crawl the updates page or published blog of the website

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Just to recrawl your webpage fastly