The acronym stands for the Certified Information Systems Security Professional. The CISSP Certification was designed to recognize individuals on their mastery of an international standard for information security and understanding of the 10 information security domains.
The Certified Information Systems Auditor, CISA, is a globally accepted standard of achievement from ISACA and certifies individuals who demonstrate proficiency in the most sought-after skills, information systems audit, control and/or security. CISM, the Certified Information Security Manager, is a management level credential from ISACA and certifies the individual knowledge and ability in information security management and consulting.
You can either retake and pass the examinations every 3 years, OR earn 120 Continuing Professional Education (CPE) credits over a 3-year period. Moreover, you need to pay the annual maintenance fee for these certifications as well.
You can take information security & control educational courses, attend security seminars or conferences, participate in professional assoication meetings, etc to earn the CPEs.