Search engines see a domain and its subdomains as two different websites. This can cause them to see duplicate content, which can negatively affect your search rankings.

The different versions of hinet.tw (with and without www. ; http and https ; even with and without trailing slash) do not direct traffic to the same URL. A fix is crucial.

Use the rel="canonical" tag to tell search engines which is the definitive version of your page. Use a 301 redirect to divert traffic from any secondary domain.

The robots.txt file is a simple text file placed on your web server which tells webcrawlers like Googlebot if they should access a file or not.

Improper usage of the robots.txt file can hurt your ranking. The robots.txt file controls how search engine robots see and interact with your webpages.

This file is mentioned in several of the Google guidelines. This file, and the bots they interact with, are fundamental parts of how search engines work.

HTML defines six levels of headings. A heading element implies all the font changes, paragraph breaks before and after, and any white space necessary to render the heading.

The heading elements are <H1>, <H2>, <H3>, <H4>, <H5>, and <H6> with <H1> being the highest (or most important) level and <H6> the least. They are used to help users and search engines to read and understand text.

For example, they act as signposts for the readers and make it easier for people to understand what a post or page is about.

Headings also define which parts of your content are important, and show how they're interconnected.

They are one of the key signals, along with many others, used by Google's search algorithm.

Here are some heading tags best practices.

Although Google says social media is not a direct SEO ranking factor, the correlation between social signals and ranking position is extremely high.

Social media affects SEO in the sense all of the shares add up to more visibility for your content.

If lots of people share your content, then it’s likely more people will link to it, and links are a very important SEO ranking factor.