Dating method
Typology
Comparing the shape of buildings, tools, or images with others that already have a proposed date. It is a web of comparisons, and the web can be circular.
How it is used
If two distant sites share a distinctive pillar shape, a tool form, or a way of building a bench, they are often placed in the same broad period. That is a hypothesis of connection, not a measurement.
The comparison is only as strong as the dated anchors it leans on. If those anchors were themselves dated by similar comparisons, the argument does not gain a new clock.
What would make it firmer
Secure radiocarbon or other absolute dates on the compared objects, in sealed contexts, at more than one site. A match of form without those dates stays a suggestion.