Random thoughts on backlinks:
Backlinks to your site are generally good. In general, the more backlinks to your site, the higher search engines will rank it. However, backlinks can be bad too. Example, If you have a site that has nothing but links to other sites, it is generally accepted that your pang rank goes down. It would be good though if you had a site full of links, to require their sites to link to yours.. This way your pagerank will not be bad.
Some good ways to get backlinks to your site are through social networking sites, dig type sites, and forum signatures. Something to consider too is the pagerank of the sites that are linking to your site. Not all backlinks are equal, and they carry different weights. In some cases, it is better to get 5 backlinks from renound, established, high ranking sites, than to have 20 links from sites just starting up.
There is a lot more on backlinks, a whole theory, and how different search engines react slightly different to sites/links, how the different sites are weighed, the frequency, and how fast the links appear, etcโฆ there is a lot more to it, but this has been just a few of the thoughts off the top of my head. Hope it helps!