Links from other sites to yours are a critical aspect of search engine optimization. A couple of links will help the search engines find your sites, but lots of links will show them that your site is a central, important resource for particular topics.
The more incoming links you have from credible organizations (that is to say, organizations that show up high on search engines themselves), the higher you will be listed in search results. To check to see the links that Google has indexed for your site, enter “link:www.yourdomain.org” into the Google search bar. The resulting list doesn’t include every link from every site, but is a guide to the approximate quantity of high-quality links.
How do you get people to link to you? As we mentioned above, there are likely a number of organizations that have a list of organizations like yours. Ensuring you’re included in all the relevant directories is a good start. See if partner organizations will link to you. Do a search on the phrases for which you’d like to be found and look for ways to get the organizations at the top of the search results to link to you. Think through content you could provide — perhaps reports, articles, toolkits, directories of your own — that would be so useful that organizations would be inspired to link to it.