The keyboard's different variations have their own distinct characteristics, with the vast majority having a buckling-spring key design and uniform profile, swappable keycaps.

Model M keyboards are notable among computer enthusiasts and frequent typists due to their durability, typing-feel consistency, and their tactile and auditory feedback.

[1] The popularity of the IBM PC and its successors made the Model M's design influential: Almost all later general-purpose computer keyboards mimicked its key layout and other aspects of its ergonomics.

Principal design work was done at IBM in 1983–1984, drawing on a wide range of user feedback, ergonomic studies, and examination of competing products.

From about 1994 onwards, flat non-detachable cables were used to reduce manufacturing costs; however, IBM retained its 101-key layout, never implementing the Microsoft Windows keys common on other keyboards from that time.

On March 27, 1991, IBM divested a number of its hardware manufacturing operations, including keyboard production, forming Lexmark International.

In 1995 Lexmark made the most sweeping design change in the Model M's history, altering the size and location of the internal controller board.

While the new "press-fit" design successfully lowered manufacturing costs by eliminating the two ribbon cables and separate LED daughterboard of older versions, the controller's new card-edge connector proved to be a failure point that shortened the keyboard's average lifetime.

The classic era of the Model M is generally considered to have ended with this change, though a few on the older pattern continued to be made at Greenock and Guadalajara until 1999.

Unicomp continued to use the original IBM machinery to produce Model Ms, leading to a gradual decline in quality as the tooling became worn.

"[citation needed] IBM released the standard and Space Saving Model M's in an alternative 'gray/pebble' color for use with their Industrial computers, designed to conceal discoloration from handling in production environments.

Other variable features include a grounded spacebar and, on some later models, drainage holes to deter damage from spilled liquids.

[27] Thanks to the M's design, including its heavy steel backplate and strong plastic frame, many early Model M Keyboards are still functional four decades past release.

Unlike more common and lower-end rubber dome designs, buckling springs give users a notable tactile and auditory feedback.

[31] Significant pressure is required to press the keys, and a pronounced sound results to help typists previously trained on typewriters who had become accustomed to that level of feedback.

Model Ms have been manufactured to quite a number of different interface and connector standards, some of which (such as the 5-pin DIN used on 5250 terminals) are poorly documented and have had to be reverse-engineered by enthusiasts.