What is duplicated content? It's basically some page you have on your website that can be accessed with different URLs. Let's say my first blog post were accessible from 3 different urls:
Seo tips & insights
Meta tags are special HTML tags that is not visible to users, however they are very important and key to helping crawlers understand content of the page. These tags can be found inside <head> tag and they appear as <meta>. They can be used to store various kind of information about your page:
The best ways to inform any search engines about new content appearing on your websites is with sitemaps. Sitemap is basic XML file that lists all URLs that are available to be crawled. It also contains information such as how often content of the page changes, when it was last updated and how important the page is to the context of your whole website.
SEO - search engine optimization is what people use to describe optimizing internet search engines to gain additional ranking and visits. It is one of the best ways to aqcuire free traffic to your website. Poorly optimized website can lead to very small or even no traffic to your website.