Microsoft Certifications are earned by passing exams aligned to a specific certification. The process of earning certification has changed multiple times since its inception.
The current iteration was introduced September 26, 2016, when Microsoft announced that it was retiring all existing MCSE and MCSD certifications, introducing new pathways, and changing the way individuals earn and maintain those Microsoft certifications. Under the new process, the number and selection of exams required to achieve a Microsoft certification varies.
MCSA certifications require the individual to pass two or more exams in order to achieve the credential. Depending on the MCSA selected, individuals are either required to pass a set pathway of exams, or can choose from a pool of exams known as electives. MCSE and MCSD certifications now only require individuals to pass a single exam, each certification has a pool of aligned elective exams that the individual can choose from.
Historically, MCSE and MCSD credentials required the individual to recertify after a period of two to three years in order to keep the credential in the "Active section" of their transcript. Under the new system, the MCSE and MCSD credentials no longer have a recertification requirement, they remain on the "Active transcript" of the holder, once gained. Individuals instead can now re-earn a certification every year by passing an additional elective exam. It was done to reflect the increasing cadence of updates to Microsoft products and services, where products like Microsoft Azure are adding new features every 48 hours.