Increasingly it seems as though every organization, profession and service is subject to a mounting number of metrics and performance indicators. League tables are no longer reserved for the winning and losing of sports teams, but are used to make comparisons between a host of different bodies, from hospitals and schools to train companies and countries. The growth and interest in new metrics and indicators has been facilitated by the growth and interest in the web. The web facilitates the sharing of established metrics and data; a service such as Google Public Data (www.google.com/publicdata) now provides a userfriendly front end to a wide range of public data, enabling the simple comparison of countries according to features as diverse as the number of daily papers sold per person, to the contribution of renewable energy to a country's energy supply. The web enables the soliciting of new data; Web 2.0 services have facilitated the ranking of politicians according to their ‘hotness’ and professors according to their helpfulness. Most importantly, the web also provides new media for analysis; in the same way the traditional media of books and journals provided the basis for new metrics, such as the number of books published in a country or the number of citations a journal receives, so new media such as web pages and blogs provide the basis for a host of new metrics. These web metrics can be far richer than those associated with traditional media as a greater variety of data can be collected at increasingly fine levels of granularity.

This book demonstrates how a host of new web metrics can be an important addition to the library and information professional's skill set. Web metrics can enable librarians to improve the online service they provide to their stakeholders and demonstrate the impact of their services to managers and policy makers; web metrics can be used to help identify the most relevant resources in a field and demonstrate the value of their own online offerings. The library and information professional's online presence now comprises a wide variety of genres. Many libraries have Facebook and Twitter accounts, some host blogs and wikis, and a few make use of the newer social media services such as Pinterest or Google Plus.