So I went over this a little in my post about crochet tools, but given the comments I got in reference to this particular subject, I have decided to devote an entire post to it.
A crochet hook, in it’s most basic form is a tool consisting of a slender handle with a hook at one (or both) ends, which is then used to pull thread or yarn through loops to create various stitches. The sizes, handles, and materials can vary and each has its own benefits and drawbacks from the ease of use to price and comfort.
Crochet hooks come in 4 general materials steel, aluminum, plastic and wood, though there are more.
Steel hooks are the smallest and mostly used in fine thread crochet such as lace and doilies. The sizes run 0.6mm (size 14) to 3mm (size 00).
Aluminum hooks are available in a large range of sizes. These allow you to crochet smoothly and quickly.
Plastic crochet hooks are available to the most common sizes and the jumbo sizes. These are usually large and hollow to keep it light weight.
Wood hooks tend, in general, be the most expensive option. They are also the smoothest option and have a natural warmth to them.
There is a crochet hook type known as Ergonomic. this type is shaped in a way to reduce the amount of stress on the hand and to reduce risk of injuries.

There are two types of crochet heads, rounded and pointed. Hooks with a rounded head is ideal for plied yarns that are prone to spitting, Pointed heads and ideal for crocheting really dense fabric.
As you can see from the above photo between the shaft and the head is the throat. There is two types of throats for a crochet hook, in-line and tapered. An in-line throat has more of a rigid decrease that tends to have a snug hold on the yarn. The tapered throat is easier for beginners as the yarn doesn’t slide off as easy. These are also good for finer weight yarns.

Note: You DO NOT need to use a tapered hook, even if you are a beginner. Try both types and find what is easier for you. I am partial to tapered hooks, however I do own a few tapered in my collection.
In general there are two types of ways to hold a crochet hook. A pencil grip and a knife grip. Both are held exactly like you think.
I don’t hold my hook in either of these methods, as I am left-handed and was taught by right handed people, so I hold my hook with my right hand in a vise-grip like manner. Try both general methods with you dominant hand and if neither of those on comfortable, find what works best for you.
I left this for last because it can get complicated. The sizing of crochet hooks can vary from country to country and manufacturer to manufacturer. I could spend pages going through the differences, but instead, I scoured the internet and found this helpful guide to crochet sizes and the conversions between the hooks in the United States and the United Kingdom.

As you can see, while both countries use MM measurements, the US uses letters and numbers in their sizing and the UK uses just numbers.
As promised I kept this somewhat short and hopefully easy to understand.
That’s it for now. I hope everyone stays safe in these odd times and I’ll see you on the social media or my next blog post.