Because the wing tip shape influences the size and drag of the wingtip vortices, tip design has produced a diversity of shapes, including: Winglets have become popular additions to high speed aircraft to increase fuel efficiency by reducing drag from wingtip vortices.
Wing tips are also an expression of aircraft design style, so their shape may be influenced by marketing considerations as well as by aerodynamic requirements.
On fighter aircraft, they may also be fitted with hardpoints, for mounting drop tanks and weapons systems, such as missiles and electronic countermeasures.
Some uncommon designs, like the Rutan Quickie, and Convair XFY placed the main landing gear in the wingtips.
Some early World War I aircraft used wooded skids on the wingtips to minimize damage on ground looping incidents.