Most of a spec sheet is noise.
We tell you which part.

A two-digit code for resistance to solids and water. The first digit covers dust on a scale up to 6, the second covers water on a scale up to 9, and an X in either position means that property was never tested.

→Matters if you sweat in them or get caught in rain, and IPX4 is the sensible minimum. Past IPX7 the extra protection rarely applies to how earbuds are actually used, and the seal degrades with heat cycling and age regardless, so read the rating as a starting condition rather than a permanent property of the product.

How long a pixel takes to shift from one shade to another, quoted in milliseconds. The advertised figure is the single best-case transition, measured with the overdrive circuit set aggressively enough to cause visible artefacts.

→Almost never as printed. It is worth caring about the underlying behaviour if you play fast games on a VA panel, where dark transitions genuinely lag. For desktop work it is irrelevant, and the number itself is not comparable between manufacturers, since none of them publish the test conditions.

How many movement steps the mouse reports per inch of physical travel. It is a sensitivity setting, nothing more. CPI, counts per inch, is the technically correct term for the same thing.

→Matters only in that the range must cover your preferred setting, which for most players falls between 400 and 1600. Past roughly 3200 the extra steps buy nothing useful: the engine multiplies raw counts by a sensitivity value anyway, and pushing that value very low to compensate for a huge DPI figure just makes sensor jitter a larger share of your input. A five-digit headline number is telling you about a marketing budget.

A shared language that lets devices from different companies describe themselves to any compatible controller, carried over normal home networking rather than a special radio.

→Worth caring about when you want a device that keeps taking commands from inside your house during an outage and can be joined to more than one ecosystem. Largely irrelevant if you were always going to live in one brand's app, because the Matter view of a device is usually a stripped-down version of it.

A count of electrical charge stored in the internal cells, measured at the cells' own voltage of roughly 3.7 volts.

→Useful only for comparing two banks of the same battery chemistry. It is close to meaningless for predicting how many times your phone will refill, and it is the number marketing leans on precisely because it sounds larger than reality.

A standardized brightness measurement averaged across nine points of a full white test field, with a defined test procedure behind it.

→It is the only brightness figure worth comparing between products, and it is measured in the brightest, least color-accurate picture mode, so expect less in normal use. It stops mattering once you are in a fully dark room at a modest image size, where almost any current projector is bright enough and contrast becomes the limiting factor instead.