Indeed, the oldest known forms of the Latin alphabet itself of the 7th to 6th centuries BC, in the Duenos and the Forum inscription, still write ⟨r⟩ using the ⟨P⟩ shape of the letter.

The descending stroke of the Latin letter ⟨R⟩ has fully developed by the 3rd century BC, as seen in the Tomb of the Scipios sarcophagus inscriptions of that era.

In handwriting, it was common not to close the bottom of the loop but continue into the leg, saving an extra pen stroke.

A calligraphic minuscule ⟨r⟩, known as r rotunda ⟨ꝛ⟩, was used in the sequence ⟨or⟩, bending the shape of the ⟨r⟩ to accommodate the bulge of the ⟨o⟩ as in ⟨oꝛ⟩, as opposed to ⟨or⟩.

Other languages may use the letter ⟨r⟩ in their alphabets (or Latin transliteration schemes) to represent rhotic consonants different from the alveolar trill.

The doubled ⟨rr⟩ represents a trilled /r/ in Albanian, Aragonese, Asturian, Basque, Catalan and Spanish.

Usually at least two of them are present in a single dialect, such as Rio de Janeiro's [ʁ], [χ], [ɦ] and, for a few speakers, [ɣ].