High Strength. The sutures (stitches) are usually stronger than the skin. The secret to a good repair is layered closure with sutures of the appropriate strength. Smaller stitches are not as strong, but are less likely to leave a mark. Be very careful to prevent further injury to the area. If the stitches pull through, delayed wound healing and a bigger scar are likely.
Strong. Strong sutures are usually used for lacerations their strength depends on material and thickness. In many cases the limiting factor is the strength of the tissue sutured. This depends on depth of placement, number of sutures and closeness to edge of laceration. On some areas like the face a fine and light suture may be used to improve appearance after healing. Appropriate strength is chosen.
Variable. Sutures have variable strength depending on the type used. Some are permanent and will keep their strength until removed. Some are absorbable and will lose their strength over a given amount of time. Ususally the suture placed is enough to keep the wound edges together. However, any sheer force can tear even the strongest closure as the sutures may pull through the tissue.