The GCFW, GCFA, GCIA, GCUX, GCIH, etc. are a sampling of advanced cybersecurity certifications offered by GIAC (SANS Institute).
GCFW, etc. certification programs are intensive ones geared toward technical proficiency in specific areas. They individually cover firewalls/VPNs, IDS/IPS, Unix security, forensics, and incident response to name only a few such coverage areas. These certification programs of the larger, more prominent GIAC (SANS Institute) ones are geared to veteran professionals and are said to be held by a limited number of persons.
GCFW, etc. are offered by the Global Information Assurance Certification (GIAC) entity that the for-profit SANS Institute created to support impartial professional certifications in the realm of information security. The requirements for these tests include two 100-question exams that are pen-book/open-Google taken online, and a fee.
“GCFW, etc. are professional certifications for information security professionals. The way these certs differ is that they each focus on a particular specialization within the field of cybersecurity, for example remote access security or Unix system security.”