Incoming links are links pointing towards to yours site. The number and relevancy of those links can be used as an indication of the popularity and importance of your website. Search engines will give credit to websites that have a good number and quality of incoming links.
Quality vs Quantity
The relevance of a site regarding incoming links is not based on the amount of links but rather on the quality. The higher the relevance of an inbound, the greater their quality and greater the value for the search engines algorithms that eventually will provide a better ranking for keywords.
How to get incoming links?
There are 3 ways to get incoming links in your website
1) Link exchange with business partners
2) Paid directory submission
3) Free directory submission
A few types of submission process:
General Directory Submission deals with all sorts of business so is not recommended to get qualify incoming links.
Niche Directory Submission submit your site to particular categories under which your site is well matched, there is a better chance to get qualify links back.
Page Rank Directory submission: the main purpose of sending our site to a directory is to get qualify links make sure the directory has a high page rank in order to get good results.
For more information, watch this video: