Canonical URL, which is also known as a canonical tag, is an HTML element that is used to prevent duplicate content issues. This tag is used when multiple versions of the same page are available over the internet.

It enables you to select the best URL as a canonical URL out of the several URLs of the multiple copies of a webpage. When you mark one version or copy as canonical version, the other versions are considered the variations of the canonical or original version by the search engine. Thus, it is used to resolve content duplication issues.

In this image, we have marked the URL of the page "www.example.com/toys/cars/yellow "as canonical URL. So, Google will consider it the original page and the other two pages as its variations, not the duplicates.

Meta descriptions, which are also known as HTML attributes, provide brief information about the content of a web page. They act as preview snippets of the web pages and appear under the URL of your page in SERPs.

A relevant and compelling meta description brings users from search engine result pages to your website, and thus it also improves the click-through rate (CTR) for your webpage.

• Quality Content
• Quality Backlinks
• Mobile Friendliness or Optimization
• Page Speed
• PageRank

Google has many factors in its algorithm to rank the websites in SERPs. Using its algorithm, it finds the relevant results for the users' queries.

Google keeps updating its ranking factors to give users the best experience and to put a check on black hat SEO techniques. So, Google displays results on the basis of ranking factors such as content, backlinks and mobile optimization.

A sitemap refers to the map of a website. It is the detailed structure of a site that includes different sections of your site with internal links.

An HTML sitemap is an HTML page that contains all the links of all the web pages of a website, i.e., it contains all formatted text files and linking tags of a website. It outlines the first and second level structure of a site so that users can easily find information on the site.

Thus, it improves the navigation of websites with multiple web pages by listing all the web pages in one place in a user-friendly manner. The HTML sitemaps provide a strong foundation for all the web pages of a website and are primarily concerned with users.

An XML sitemap is exclusively designed for the search engines. It facilitates the functionality of the search engines as it informs the search engines about the number of web pages, the frequency of their updates including the recent updates. This information helps search engine robots in indexing the website. See the image of the sitemap of a website:

301 redirecting is a method of redirecting users and search engines from the old page URL to a new page URL. The 301 redirect is used to pass the link traffic from the old URL to the new URL. It is a permanent redirect from one URL to another site without typing the URL of the new site. It helps you maintain the domain authority and search rankings when the URL of a site is changed for any reason.

Furthermore, it allows you to associate common web conventions with one URL to improve the domain authority; to rename or rebrand a site with a new URL; to direct traffic to a new website from other URLs of the same organization. So, you must set up a 301 redirect before moving to a new domain.

A 404 error is an HTTP response status code which indicates that the requested page could not be found on the server. This error is generally displayed in the internet browser window just like web pages.

HTTP 404 error is technically a client-side error which means it is your mistake, i.e., the requested page is not present in your website. If you had maintained that page in your site, it would have been indexed by the crawler and thus would have been present in the server. Furthermore, you also receive this error, when you mistype a URL or when a webpage or resource is moved without redirecting the old URL to the new one. So, whenever you move your webpage redirect the old URL to the new URL to avoid this error as it may affect the SEO of your site.