Emerging Sources Citation Index (ESCI) is an additional new database which was launched in late 2015. According to the publisher, it was created to discover new areas of research in evolving disciplines, as well as relevant interdisciplinary scholarly content across rapidly changing research fields. Thus, journals accepted for the ESCI should have minimal selection criteria: have to be peer reviewed, follow ethical publishing practices (not predatory journal), meet technical requirements (PDF/XML formats), have metadata in English language and be recommended by scholarly audience of Web of Science users.
Journals indexed in the ESCI later can continue to be considered for inclusion in other Web of Science Core Collection databases such as SCIE, SSCI, and AHCI, which have rigorous evaluation processes and selection criteria.
ESCI journals will not receive Impact Factors, however the citations in these journals will contribute to the Impact Factors of others.
Indexing journals in the ESCI improves the visibility of a journal in scholarly society, shows quality and provides coverage of relevant titles in evolving disciplines.
You can find out more about Emerging Sources Citation Index here.