jira client basic clarification required?

[Tarun Kumar]

what is the difference between jira-rest-java-client-core and jira-rest-java-client & jira-rest-api?

which one is latest one jira-rest-java-client-core or  jira-rest-java-client? and which one is best?

is it necessary to use jira-rest-api with jira-rest-java-client-core or jira-rest-java-client ? 

what is the best and what to use if i'm getting started using with jira?

[Nic Brough -Adaptavist-]

The client programs are libraries trying to help you with connecting to Jira over the Jira REST api.

Latest or best don't make a lot of sense, you need to use the one that is compatible with the version of Jira you are working with.

You do not need to use the clients at all, the Jira REST API is something you can talk to with any REST call you want.