What type of hair extension is typically added by sewing into braids or a track?

The correct answer is wefts, as they are specifically designed to be sewn into braids or tracks for hair extensions. Wefts come in long strands of hair that are typically secured at one end, allowing for easy attachment to the natural hair through methods such as sewing or gluing. This technique involves creating a base with braids or a track to which the wefts are sewn, providing a secure and long-lasting form of hair extension.

In contrast, clips are temporary attachment methods that can be easily added or removed, while micro-links and fusion methods involve using small strands or bonds that connect to the natural hair without sewing. These methods do not involve braiding and require different application techniques. Thus, wefts are the most appropriate choice when referring to extensions added specifically by sewing into braids or a track.