IBM traces its roots to 1911 and the punched-card tabulating machines that counted the US census and ran the back offices of the industrial age. Under Thomas J. Watson it became International Business Machines in 1924 and, for most of the 20th century, was synonymous with business computing itself.
System/360 — betting the company
Its defining moment came in 1964 with System/360: instead of incompatible one-off machines, IBM offered a family of computers that all ran the same software and could be scaled up without rewriting everything. It was a colossal, risky investment — and it made IBM the dominant force in enterprise computing for a generation, establishing ideas (compatible architectures, an operating system, peripherals as an ecosystem) that still shape the industry.
The PC — a standard it didn't keep
In 1981 the IBM Personal Computer legitimised the microcomputer for business. Crucially, IBM built it from off-the-shelf parts and licensed its operating system from a small company called Microsoft — decisions that created the open "PC clone" market and, ultimately, handed the profits of the PC era to Microsoft and Intel rather than IBM.
Reinvention
IBM has survived by repeatedly reinventing itself — exiting PCs, moving into services, semiconductors and research (it holds a long record of US patents), and staking public milestones in AI with Deep Blue and Watson. Today it focuses on hybrid cloud, enterprise AI and quantum computing research — still, more than a century on, a fixture of the corporate data centre.