Squid jigs are specialized lures that attempt to target squid by imitating the predator's prey (usually prawns).
The jig works differently than regular hard body fishing lures in that it does not have hooks with barbs, but a series of up-turned spikes that attach to the tail of the lure.
The jig is usually cast out into an area that is thought to be squid habitat, and slowly retrieved. When a squid attempts to capture the jig by shooting its tentacles (the two longer arms with suckers on the ends) at the lure, they are entangled in the spikes. As long as proper tension is kept on the fishing line, the squid cannot escape and can be taken aboard the kayak.
Squid jigs can be a variety of colours and sizes, although the colour pink in the 2.5 size would arguably be the most popular selection. It appears that jigs manufactured by brands such as Yozuri and Yamashita do tend to outperform jigs made by cheaper brands. For the beginner looking to make an attempt at squidding for the first time, a Yozuri 2.0 (or 2.5) in pink would be a good jig choice to start with.
There is also a version that uses a single deadbait such as a pilchard instead of a lure but works on the same basic principles of entangling the squid's tentacles.
Below: A common squid jig.
Although debatable, some believe that it is a common mistake to choose a squid jig that is too large for the intended target. The most popular squid jig size, judging by availability, is the 2.5. This size jig will certainly attract mid-sized and large squid, however, using a smaller jig (such as the yozuri 2.0 pictured below) will account for both small and large squid alike.