In its simplest form, link reclamation is the practice of picking up links from unlinked brand mentions and citations on other sites.
You can find these in a number of ways:-
Firstly, you can do a simple Google search for your brand name, or website name (always good to do periodically), and go through the results looking for opportunities.
For ongoing opportunities you should set up a series of Google alerts for your brand name and any other ways in which your website might be mentioned (for example, the names of members of your team). Again, notwithstanding the opportunity to pick up links, this is good practice as you certainly want to know what people are saying about you and your brand around the web.
When you find an unlinked mention, simply reach out, thank the webmaster for the mention, and ask if they could include a link for any of their visitors who wish to find out more. You'll get a very high conversion rate on this.
Aside from link reclamation on external sites, you can often reclaim links on your own website!
When you move things around, which happens from time to time, URLs change and links get broken. You can use Ahrefs to find broken links to your site.
Type in your domain in site explorer and then click on 'Broken Backlinks' under 'Inbound Links'.
Our friends at Moz currently have 3,483 broken links pointing at their site (going to pages returning a 404 error). If they fixed these and added 301 redirects for the old URLs to the new ones, they would perhaps get a nice little rankings boost. But hey, that's up to them! ;-)
Nice 404 page mind you…
Further Reading