The neckline is the top edge of a garment that surrounds the neck, especially from the front view. Neckline also refers to the overall line between all the layers of clothing and the neck and shoulders of a person, ignoring the unseen undergarments.
For each garment worn above the waist, the neckline is primarily a style line and may be a boundary for further shaping of the upper edge of a garment with, for example, a collar, cowl, darts or pleats. In that respect it is similar to the waistline and hemline.
these have a curved U-shape, with the arms of the U hanging on the shoulders. The depth of the U can vary, ranging from demure styles to plunging.
V-neck (2–4 linear edges, side edges diverge)
originate from the middle east, these are formed by two diagonal lines from the shoulders that meet on the chest creating a V shape. The depth of the V can vary, ranging from demure styles to plunging. The surplice version of this neckline (known as a portrait neckline) is an alternative. The V may also be truncated by a small bottom edge, forming a trapezoid.
square neck (linear side edges neither converge nor diverge)
these are characterized by three linear edges, the bottom edge meeting the side edges at right angles. The bottom edge cuts across the figure horizontally and the side edges pass over the shoulders. A special case of this is the slot neckline, in which the side edges are very close (roughly the width of the collar-bone points), forming a narrow slot.
Deep V neckline
A halter top
A woman in a tube top
T J Hart in a plunging neckline dress
deep or plunging neck
these are low necklines, in either V, U or square shapes, that reveal various amounts of cleavage, and some even extending to the natural waist line.
these have a high, wide, slightly curved neckline that pass past the collarbones and hang on both shoulders, and are also called bateau necklines or Sabrina necklines. A variation is the portrait neckline.
off-the-shoulder (one edge, nearly linear. Also known as Carmen neckline)
these are similar to boat necklines but are significantly lower, below the shoulders and collar bone. Usually these pass over the arms but, in the strapless neckline style, may pass under the arms. These necklines accentuate the shoulders and neck of the wearer.
one-shoulder necklines (one edge, nearly linear)
these are asymmetrical linear necklines that cut across the torso diagonally, usually from one shoulder to under the other arm.
halter necklines (linear, side edges converge on neck)
these feature a V-neck or scoop front neckline with straps which wrap around and connect at the nape of the neck.
these have a curved bottom edge that is concave down and usually doubly scalloped to resemble the top half of a heart. The side edges often converge on the neck, similar to halter necklines. Sweetheart necklines accentuate the bosom.
these are similar to halter necklines, but the converging diagonal lines meet in front of the neck, forming a "keyhole". More generally, these feature a central hole, usually just below the collar bones. These necklines are seen infrequently.
these are similar to how a bathrobe's neckline is formed by one side of the garment overlapping the other. For a dress, the lower layer is usually sewn to the top layer just under the bust.
The shape of a necklines can be modified in many ways, e.g., by adding a collar or scarf, overlaying it with a gauzy material or decorating the edges with scallops, picots or ruffles. The neckline can be a sharp edge of fabric or a more gentle cowl, and can also be accentuated by pattern(s) in the fabric itself.
The neckline can frame the shoulders, neck and face, and change their apparent width, height and angularity. It is generally advised that the neckline shape be chosen to balance the wearer's natural features. Thus, a face with round curves is well-framed by an angular (linear) neckline and collar, whereas an angular face is softened with curves. Similarly, a short neck and face will appear lengthened by necklines with strong vertical (or nearly vertical) lines, such as a plunging V neckline (or a long knotted scarf or necklace); conversely, high necklines such as the jewel or turtleneck types balance long faces. Broad shoulders can seem more narrow with style lines that converge inwards (e.g., the halter neckline), whereas pear-shaped figures can be balanced by diverging or horizontal lines, e.g., an off-the-shoulder or boat neckline.
The designer should also consider the amount of decolletage the wearer would like and whether the visibility of undergarments (such as bra straps) is relevant. These factors may influence the depth and width of the neckline, respectively.