Canonicalization refers to the technique through which it the content can be prevented from googlebots to avoid getting indexing in google search result pages. Canonical tag is often embed on top of the head section of source code. However, canonical tag is already embedded on various web designing tools.
Canonical tag is also known as “rel canonical” and is a method of telling googlebots that a particular URL reveals the master copy of a page. For instance if you have written two pages of contact form which tells yields different use, then you might have to put canonical tag to make search engine aware that your content of both URL is not same or duplicate. It is helpful in online market and is adopted by most of the webmasters.
Canonical tag is confusing in the manner that most people are not able to understand that why would anyone duplicate a page. The problem is that human being tends to think that all the URLs represent a single page while search engines crawls each URL as unique page. So without this tag, googlebots will not index your web page because it will assume the content is duplicate. Now- a-days most of the code-driven website has inbuilt feature of canonicalization. Most of the website automatically adds tags and allows multiple URL to the same content.
Some of the benefits of this tag are briefly discussed in my article:
1. The canonical tag (aka rel=’canonical’) tag allows the search engine to decide which page has original content and assists in ranking in search engine result pages. Product pages may often deal with this type of problem; therefore the necessity of this tag has been a need of an hour.
2. Canonicalization helps to improve your sites performance by making search engines aware that your content is original and free from plagiarism. This tag is especially beneficial for those that have multiple home pages in search engine result page (SERP). For instance it is usual in most of the websites to have the pages appearing in SERP like /www.yoursite.com and yoursite.com/
The above two links are considered as single webpages. But with the help of canonical tag will enable your link to treat only as the homepage. Without this tag will result in lower ranking and even penalization may occur on your site.