Kakka is the sixth letter of the Gurmukhi painti and the first of the five ordered consonant series. Those five groups are the structural heart of any Brahmic script. Each collects the consonants made at one point in the mouth, and within each group the five members always run in the same order: voiceless unaspirated, voiceless aspirated, voiced, voiced aspirate, and the nasal made at that same point. Kakka opens the first group, the velars, made at the back of the mouth, and each group takes its name from its own first letter, so the velars are the kavarg.
Kakka itself writes a plain k with no breath after it. Its shape is a vertical stem dropped from the headline with a loop to its left, and that combination of headline and stem is the structural signature of the script: Gurmukhi words are written from a continuous horizontal line, with the letters hanging beneath it, which is why a Gurmukhi page reads as a series of ruled bars rather than as separated shapes. Because Kakka opens the ordered part of the alphabet, it is the letter by which the whole system of series is taught. The headline itself deserves a word, because it is not a decorative rule. It is written as part of each letter and joined across the word, so the line grows with the writing rather than being drawn first, and word boundaries in Gurmukhi are marked by breaks in that line rather than by the spaces a Latin reader looks for. That is why a Gurmukhi text set with the headline broken is not merely ugly but harder to parse.