A fret in heraldry is a classic geometric charge built from a bend and a bend sinister interlaced with a mascle, creating a neat piece of “woven” structure on the shield (Mistholme: Fret). It reads instantly as interconnection: strands crossing, holding, and reinforcing one another. That makes the fret a natural emblem for ideas like unity, mutual support, steadfast bonds, and faithful service, whether those bonds are family ties, alliances, or obligations of office. Because it is fundamentally an interlacing device, it also lends itself to the broader heraldic theme of order imposed on complexity, a tidy pattern that suggests disciplined judgment rather than raw force.

Heraldically, the fret matters because it is not just “some lattice.” It is a specific constructed form, and older sources sometimes associate it with the phrase “Harrington knot” in connection with the medieval Harringtons (Mistholme). A fret can also be confused with fretty, which is a field treatment of repeated interlacing; historically the two have been close enough that artists and compilers sometimes drift between them, so blazon and good drawing conventions help keep the intent clear (Mistholme). For visual reference, see Mistholme’s illustration (image).

As an example in armory, “Argent, a fret gules” is recorded as the arms of the Blake family (Wikipedia: Ordinary (heraldry)). That sort of bold, high-contrast fret is typical: it sits centrally, reads cleanly at distance, and makes a memorable “signature” for an armiger. If you want additional diagram-style guidance on geometric charges in the same design family, the reference PDF linked from Wikipedia is also useful for artists and blazon readers (HeraldicArt: Geometric Charges).