Altmetrics include a much broader spectrum of measurements like citation counts, web based references, article views/downloads, social media mentions, news media mentions, etc. Traditional means of measuring the quality of new knowledge like the impact factor and h-index are being more effective and more meaningful through the addition of new, social media based altmetrics. altmetrics could reflect an alternative dimension of the research performance, close, perhaps, to science popularization and networking abilities, but far from citation impact. altmetrics are especially encouraging for research fields in the humanities that currently are difficult to study using established bibliometric methods. In this paper introduce altmetrics, their uses and its possible implications in libraries. The present study is based on review of published work in the field of altmetrics, bibliometrics and library and information Science.