The Emerging Sources Citation Index (ESCI) was launched in late 2015 as a new database within Clarivate Analytics’ (formerly Thomson Reuters’) Web of Science. The selection process for ESCI is the first step in applying to the Science Citation Index. Journals accepted for coverage in ESCI must be peer reviewed, follow ethical publishing practices, meet technical requirements, have English language bibliographic information, and be recommended or requested by a scholarly audience of Web of Science users.

Which bibliographical database is more valuable would very much depend on institutional policies. And these might differ from one university to another.  

Generally, journals included in SCOPUS are definitely "in". This is a reputable and widely-recognized database. University rankings are based on publications in SCOPUS. 

Also, many of the journals in Web of Science (WoS/WoK) core collection are prestigious (and also "in"). But this is not so with journals included in the ESCI database. These journals are given a trial period after which they either will get their impact factor in the WoS/WoK database or they will be dropped altogether. 

So (leaving aside WoS/WoK core databases), when searching for a publishing venue it would be good to look for journals that are indexed in SCOPUS (primarily) because these journals are already "in". If the same journal is listed in ESCI -- consider it as an additional bonus.  

Dear sir,

There are many trusted factors under umbrella of Scopus, like CiteScore, Impact Factor, ..etc, but I have no idea about this indicator!!

Could you please introduce more details if any?

Emad

ESCI is a new index under the umbrella of "Creative Analytics" whic was known as thomson reuters or ISI. This umbrella is the most popular and important one. SCI and SCIE and SSCI are under this umbrella. I attended a workshop of ISI before two weeks and they mentioned four different indexes in ISI. ESCI is given to journals that are specialist in a sceince field that is not popular in all countries around the world. One of the criteria  to select a journal to join ISI is world distribution.So If a feild of a journal is only popular in a region of the world, the journal will not be popular in all the world and all of the citation will be from the same journal. In this case, the jouranl will be indexed in ISI under ESCI. This is what I understood from the workshop

DOnot forget ISI is treated higher than Scopus every where in the world specially in paper and university ranking

Thanks to Larisa Nikitina, Emad Kamil Hussein and Mohammad zakaria Masoud  for valuable comments. 

There are so many believable factors under umbrella as scopus, sci, thomasreuters etc.  ECI is also like this. 

Emerging Source Citation index (ESCI) is a part of Web of Science. It is an indexing data base of Thomson Reuters. The journals indexed in ESCI will not get the impact factor. But the papers cited in ESCI database will be included in Journal Citation Report. It is the first stage of a Journal to be included in ESCI database. Moving forward to SCI or SCIE.

Thank you vivek Krode.

The Emerging Sources Citation Index (ESCI) was launched in late 2015 as a new database within Clarivate Analytics’ (formerly Thomson Reuters’) Web of Science. The selection process for ESCI is the first step in applying to the Science Citation Index. Journals accepted for coverage in ESCI must be peer reviewed, follow ethical publishing practices, meet technical requirements, have English language bibliographic information, and be recommended or requested by a scholarly audience of Web of Science users.

The Emerging Sources Citation Index is a citation index produced since 2015 by Thomson Reuters, and now by Clarivate Analytics. According to the publisher, the index includes "peer-reviewed publications of regional importance and in emerging scientific fields".[1] It has been observed that among the databases produced by Clarivate Analytics, the Emerging Sources Citation Index is the easiest one to get into and that as a result it contains many predatory journals.

Together with Science Citation Index Expanded, Social Sciences Citation Index, and Arts and Humanities Citation Index, the Emerging Sources Citation Index is accessible through the Web of Science.

some journal in scoups is more authentic than ESCI and some are not it depend on journal not on the scoups or ESCI

Can I ask if what is the validity period of coverage of a journal indexed in the ESCI? For example, a journal was indexed in 2015 under ESCI, how long is its validity of indexing?