As a webmaster engaged in the process of optimization and link building, you'll want to measure and track your link building efforts. Keep in mind that you won't get a link every time you request one. Not only that, but if the page upon which you secure a link is not indexed by search engines, then you won't get any traffic or ranking power from that link. Some pages will be indexed by one search engine and not others, so your inbound link counts in any particular search engine will differ from all the others. In the past years, Google indexed more pages than other search engines, but that has changed as the mid tier search engines link Yahoo! and Bing began to crawl the web more deeply.
You'll use several methods to measure your inbound links. A great source is the search engines themselves. There is also specialized software for the purpose of measuring and evaluating links.