A Third Country Conversion might be necessary if you hold an ICAO licence but wish to permanently obtain a European EASA licence.
Getting a European licence may prove useful or even necessary depending on your personal situation and goals.
For instance, you must hold an EASA licence if you wish to work in the EU. (Exceptions to this might apply depending on the duration and scope of the work.)
A conversion is possible for CPL, PPL and FI licences.
An adapted training course established by CEFA based on your experience and qualifications allows you to obtain a respective EASA licence.
The prerequisites to be met depend on the type of licence you currently hold, as well as the one you wish to obtain.