Citation Index : A citation index is a kind of Bibliographic index, an index of citation between publications allowing the user to easily establish which later document cite which earlier document

Impact Factor : An impact is the average number of citations received for each published articles in that particular year. Impact factor determines the ranking of a journal in the specific category which can be found in the journal citation reports.

H-index : The h-index is an author-level metric that attempts to measure both the productivity and citation impact of the publications of a scientist or scholar. The index is based on the set of the scientist's most cited papers and the number of citations that they have received in other publications.

Scopus:

Scopus is the largest abstract and citation database of peer-reviewed literature: scientific journals, books and conference proceedings. Delivering a comprehensive overview of the world's research output in the fields of science, technology, medicine, social sciences, and arts and humanities, Scopus features smart tools to track, analyse and visualise research.
https://www.scopus.com/search/form.uri?display=basic

Web of Science:

In Web of Science has unrivalled breadth of world-class research literature linked to a rigorously selected core of journals and uniquely discover new information through meticulously captured metadata and citation connections. The Web of Science platform connects the Web of Science Core Collection to regional citation indexes, patent data, specialized subject indexes, and an index of research data sets, all in all totaling over 33,000 journals
http://login.webofknowledge.com/error/Error?Error=IPError&PathInfo=%2F&RouterURL=http%3A%2F%2Fwww.webofknowledge.com%2F&Domain=.webofknowledge.com&Src=IP&Alias=WOK5

Journal Citation Reports:

Journal Citation Reports is an annual publication by Clarivate Analytics. It has been integrated with the Web of Science and is accessed from the Web of Science-Core Collections. The JCR provides journal intelligence that highlights the value and contribution of a journal through a rich array of transparent data, metrics and analysis.
https://jcr.incites.thomsonreuters.com/

Google Scholar Citations:

Google Scholar Citations provide a simple way for authors to keep track of citations to their articles. You can check who is citing your publications, graph citations over time, and compute several citation metrics. You can also make your profile public, so that it may appear in Google Scholar.
https://scholar.google.com