Tunisian crochet is a fabulous niche of crochet that allows you to craft in a slightly different style to create fabrics that have a "knit-look" design instead of the traditional look of crochet. The way that this look is achieved is by holding your loops on your crochet hook, as you would do with a knitting needle. Because of this, you need to invest in Tunisian crochet hooks rather than just using the crochet hooks that you already have, if you plan to do a lot of Tunisian crochet.
Tunisian crochet is a lot easier to master when you have the right tools. Tunisian crochet hooks, also called Afghan crochet hooks, are longer than regular crochet hooks. They are shaped without a fat thumb grip and thus can hold many loops on the hook at a time without stretching some to different heights than others. Tunisian crochet hooks are not significantly more expensive than regular crochet hooks, and a set of them is a nice addition to your library of craft supplies.
Where to Buy
Tunisian crochet is a niche of crochet but it's become increasingly popular again in recent years, so you shouldn't have any trouble finding Tunisian hooks in any of the places where you normally buy crochet hooks. Major stores including Hobby Lobby, Michael's and Joann's usually have Tunisian crochet hooks, although some stores will have better size selections than others. You can check with your local LYS to see if they sell Tunisian crochet hooks. Of course, you can also shop online.
Remember that if you are searching online for Tunisian crochet hooks, you might want to also do a search for "Afghan crochet hooks", as the hooks may be labeled either way. Some people get confused, thinking that Afghan hooks are just for making blankets (afghans) but they're actually referencing this niche of crochet that is known by a couple of different names. Most stores these days will advertise the hooks as Tunisian crochet hooks or will use both names, but it's helpful to be aware of both terms when searching for the right crochet hooks online.
Double-Ended Crochet Hooks
You may have seen long crochet hooks that have a "hook" on either end. If you are second-guessing yourself and thinking that is what you are supposed to use in Tunisian crochet, you can trust your gut after all. Tunisian crochet worked in the round uses double-ended crochet hooks.
The extra-long crochet hooks with a hook on only one end are what you need for Tunisian crochet worked in rows. If you want to work Tunisian crochet in the round then you actually need to purchase additional supplies. You can either get a double-ended crochet hook or a circular Tunisian crochet hook, which is basically two crochet hooks connected together by a cable that runs between them. Note that these cabled Tunisian crochet hooks are also great for working Tunisian crochet in rows when your rows are very long (as in a Tunisian crochet blanket pattern, for example); the cable can hold your extra loops for you as you crochet.
Many people who are just getting started with Tunisian crochet want to know if they really have to get a special tool to do this crochet technique. The answer is, "not necessarily, but it's a good idea". Small swatches of Tunisian crochet can be done on regular crochet hooks, as long as the hooks that you have do not have very wide thumb grips—this is because you have to hold loops on the hook and large thumb grips alter the height of those loops. If you want to try short rows of crochet, as done in Tunisian entrelac crochet, then your regular hooks might work.
Learn How to Tunisian Crochet
In summary, you can technically do Tunisian crochet with a regular hook, but it's best to purchase the right kind of tools—a long Afghan crochet hook for working rows and a double-ended or circular Tunisian crochet hook for working in the round. It's wonderful that you want to give Tunisian crochet a try! Once you've purchased your hooks, you'll be ready to tackle Tunisian crochet patterns and make lots of interesting new projects.