If you're concerned that Google's move to mobile first indexing might negatively affect your site's visibility and search engine ranking...
- A link to your website is like a recommendation in the eyes of the search engines
- Not all links are considered equal, some have more ‘weight’ than others
- Anchor text will increase the relevance of a keyword through the link
Links act as recommendations to your website you are literally saying this is a good website visit it through this link.
Just as not all websites are created equally, links carry different values as well. Similar to getting a recommendation if your team leader were to recommend you to an employer it would be a good recommendation, however, the CEO may carry more weight. If a small website links to you this is always good but if you got a link from a very powerful website such as the BBC then this link would have a lot more strength and therefore impact upon your positions in the search engines.
Using anchor text for a link, such as ‘click here’ will give specific relevance to the site through that keyword, you can see this with the Adobe site where many websites have used click here as the anchor text to download PDFs therefore although the Adobe site has not got much relevance on site for ‘click here’ they still come up top for the keywords as so many people have linked to the site and passed the relevance on through the anchor text.