The cap is the final piece added to a cigar. After the wrapper has been rolled up the cigar in a spiral, the roller cuts a small round piece (or strip) from leftover wrapper and glues it over the head with a tasteless vegetable gum. The cap closes the end, holds the wrapper so it cannot unroll, and gives you a clean place to cut with a cutter. The head is the closed end of the cigar, and the cap is the piece of leaf that closes it.
Some factories apply a single cap. Others apply a double or triple cap, a finish long associated with Cuban rolling. Pigtail caps (a small twist of leaf) and flag caps are finishing styles and do not affect flavor. Pointed figurado heads, such as those on the torpedo and pyramid, also have a cap, shaped to a point.
When you cut, stay above the line where the cap meets the shoulder of the cigar. If you cut below it, the wrapper can start to unroll. See guillotine, V-cut, punch, and how to cut and light a cigar.