Google sees incoming links to your website as votes of confidence. They are a Google ranking factor.
An inbound link = a hyperlink from another website which is pointing at your website.
In general, the more inbound links you have, the better.
1. Gradually build incoming links to your website. Google doesn’t like sudden ‘spikes’.
2. Work manually (i.e. don’t use bots / software programs / suspicious services from people you don’t know).
3. Include keywords within the anchor text*, where appropriate.
4. The links should come from relevant websites.
5. The links should come from sites with high authority (i.e. credible websites).
6. Don’t use paid links.
7. Don’t use email spam to request links.
8. Do keep a meticulous record of your in-bound links.
9. Remember that links within your own website are important as well.
10. Do check from time to time that the links still work. See: https://www.brokenlinkcheck.com