Node Size (nm)
The number that used to mean something simple, and now doesn't quite
Imagine describing how fine a fabric's weave is purely by a single thread-count number. For decades, that was roughly how the chip industry described progress too, a single number, the node size in nanometres, that was assumed to directly describe the size of the smallest transistor feature on a chip. Smaller number, smaller transistor, more transistors packed into the same space, more computing power per chip.
That relationship held reasonably well for a long time, and it is the basis of Moore's Law, the observation that the number of transistors on a chip roughly doubles every couple of years. A chip made on a 28 nanometre process genuinely had larger, less densely packed transistors than one made on a 7 nanometre process, and the 7nm chip could typically pack in far more computing power in the same physical space.
In more recent process generations, the node name has become more of a marketing label than a literal physical measurement, since transistor architectures have evolved in ways that no longer map cleanly onto a single physical dimension. A modern 5nm or 3nm chip does not literally have features that are 5 or 3 nanometres across in every dimension, but the industry has kept using the naming convention because it still broadly signals a chip's generation and relative capability.
This is exactly why India's first high-volume fab, the Tata-PSMC facility, targeting 28 nanometre production, matters strategically without needing to compete at the industry's bleeding edge. 28nm chips, mature and well-understood technology by industry standards, still power the overwhelming majority of everyday electronics, cars, appliances and industrial equipment, which do not need cutting-edge 2-3nm performance at all.
Whenever a country's semiconductor strategy is described as targeting a specific node, that single number is really shorthand for an entire strategic choice, whether to compete for cutting-edge, expensive-to-build capability, or to secure reliable, still-valuable capacity at a more mature, more attainable process generation.