Some neopagans also use the triquetra in their iconology. Often it represents the three stages of life, particularly in women, described as maid, mother and crone. The aspects of the Triple Goddess are named the same, and thus it can also be a symbol of that particular concept.
The triquetra can also represent concepts such as past, present and future; body, mind and soul; or the Celtic concept of land, sea and sky. It is also sometimes seen as a symbol of protection, although these interpretations are often based on the mistaken belief that ancient Celts ascribed the same meaning to it.
Our understanding of the triquetra and other historical knots suffers from a trend to romanticize the Celts that has been going on for the last two centuries. Many things have been ascribed to the Celts that we simply have no evidence for, and that information gets repeated again and again, giving the impression of them having widespread acceptance.
While people today most commonly associate knotwork with the Celts, Germanic culture also contributed a very considerable amount of knotwork to European culture.
While many people (particularly neopagans) view the triquetra as pagan, most European knotwork is less than 2000 years old, and it often (although certainly not always) emerged within Christian contexts rather than pagan contexts, or else there is no obvious religious context at all. There is no known clearly pre-Christian use of the triquetra, and many of its uses are clearly primarily decorative rather than symbolic.
This means that sources that display triquetras and other common knotwork and give clear definition of what meaning they held to pagan Celts are speculative and without clear evidence.