Wild Thyme is common and widespread throughout the UK and Ireland.
This low-growing member of the mint family is generally found in dryish grassland, heaths and dunes, but occasionally you will also find it growing in dry stone walls. In suitable conditions it spreads rapidly via runners.

Wild thyme has square stems that are hairy on two sides, and oval leaves. The purple flower heads are rounded with individual flowers typically 5 mm across.

A taller, more strongly scented relative, Large Thyme (Thymus pulegoides) does not throw out runners and has elongated whorled flower spikes; it is more commonly found in areas with plenty of lime in the soil.
The pictures on this page were taken in Kenfig National Nature Reserve in South Wales (top) and in The Burren in Ireland (bottom).