Origins
In the smoke and confusion of a medieval battlefield, one thing had to be visible above all: the standard. This was the flag, mounted high on a pole or cart, that told soldiers where to rally. Lose the standard and the army fragments. Hold it and you hold the line.
The word comes from Anglo-French estandard, probably from Frankish *standhard — 'that which stands firm'. A standard was planted into the earth and defended to the death. The Battle of the Standard at Northallerton in 1138 was named for a ship's mast fixed to a cart, carrying the banners of St Cuthbert, St Peter, and St John of Beverley. The English army rallied around it and defeated the Scots.
Development
The abstract sense emerged by the 15th century. If a standard is the fixed point that defines position on a battlefield, then a standard of quality is the fixed point that defines acceptable performance. Weights and measures were standardised against a physical reference kept in a royal treasury — another literal standard, another thing that had to stand firm.
The word now governs modern life: building standards, accounting standards, living standards, gold standards. Each is a flag planted in conceptual ground, declaring: this is where we stand. The military origin has been forgotten, but the logic remains — a standard is still the point around which order is maintained.