Bibliometrics are a range of quantitative measures that assess the impact of research outputs using citation counts. Together with qualitative indicators of research impact such as funding received, number of patents, awards granted and peer review they assess the quality and impact of research.

Bibliometrics can be used to :

• Provide evidence of the impact of your research outputs when applying for jobs, promotion or research funding
• Find new and emerging areas of research
• Identify current & potential research collaborators
• Identify high ranking journals in which to publish
• Identify, benchmark & showcase research strengths at an individual, departmental, institutional or national level 
  • for example top authors, top institutions  in a particular field

Bibliometrics are quantitative measures that provide just one part of the picture. Ideally they should be used in conjunction with other data such as funding received, number of patents, awards granted and peer review.

Some Limitations of Bibliometrics

• Quality: high citation counts may not necessarily indicate quality.
• Differences between discipline's: some research fields cite papers more than others.  You need to compare like with like !
• Early Career Researchers may not fare so well.  You need to take stage of career into account. Altmetrics may be useful here.
• Data coverage varies: the tools used to gather bibliometric data do not cover all research areas or index all publications. The results will vary depending on the tool you use. For example University Rankings metrics are drawn from the Scopus Database.

For more check out these source's:

https://www.sheffield.ac.uk/library/research/metrics/intro

https://library.leeds.ac.uk/info/1406/researcher_support/17/measuring_research_impact

University Rankings Data: A Closer Look for Research Leaders (elsevier.com)

The Metric Tide » Responsible Metrics