Here's an overview of some of the most useful hand tools you'll need as you start woodcarving.
The woodcarving knife is usually the first tool a woodcarver will purchase. Woodcarving knives come in all shapes and sizes, but the standard size is a blade length of around 1-1/2". You'll see some blade lengths as short as 1/2" and others topping out at over 2". Typically the shorter blades will be used for detail work and the longer ones for roughing. The cutting edge of a standard carving knife is the straight side, with the spine being curved down to the point unlike some pocket knives which are the opposite, a simple thing but always take note of where the sharp edge is located. There are always some exceptions to this rule though and you'll see a few up sweep & back bent blades on the market which will have the cutting edge on the curve. A standard 1-1/2" carving knife is a good all around compromise for taking off stock and being able to have a nice tip you can control for detail work. There are also some good choices when you do want to carve your detail features. A nice detail knife will not only be around 1" or so, but will also be narrower from the cutting edge to the spine, allowing you to reach into tight areas. You can start whittling as soon as you get your woodcarving knife, but pretty soon you'll want to make some other cuts that the knife just won't be able to handle. This is when you'll want to use your gouges and v-tools.
Gouges are scooping tools that have a curved cutting edge. The shallowest of the gouges is the #3 which has just a slight "smile". The gouges get deeper with each number progression. The gouge depths are #3,4,5,6,7,8,9,10, and the deepest is a #11, also called a veiner. All of these gouges can be found in any number of widths, some of the smallest measuring in at around 1.5mm or 1/16". Don't be intimidated by the metric sizing you might run across with tools. It's common to see them sized that way and most of your standard rulers will have metric sizes listed also for comparison. Gouges come in palm tools and full sized mallet tools. Palm tools have comfortable handles that fit in your palm and allow your fingers to grip the tool close to the cutting edge for great control. The shape of these handles is really personal preference and most long time carvers don't even notice the handle in their palm any more, it's the cut of the tool that counts the most. Full sized mallet tools are longer and give the carver the option of using them with a mallet where extra force is needed, such as with harder woods or larger projects. Many carvers also use their mallet tools by hand without the mallet, again just personal preference.
V-tools (not to be confused with veiners) have a v shaped cutting edge that makes a v shaped cut that is useful for making wrinkles, hair, or fur on your carving, creases on carved clothing, separations between two elements (such as the sole of a shoe from the shoe), and details on any number of carved features. Certainly an extremely useful tool. V-tools are measured primarily by their degree of spread. A common useful spread would be 70º, although 60º (a bit narrower) and 90º (a bit wider) are used quite frequently. There are some very tight v-tools (30º) as well for specialty cuts. V-tools also come in many widths just like the gouges, some as small as 1/16" up to 2" and more. They're also abundant in palm and mallet tool configurations.
Chisels and skews are carving tools with straight cutting edges and are used when a flat cut is desired. The chisel's cutting edge is flat and runs straight across the end of the tool. The skew's cutting edge is also straight but runs upward at an angle. Though less commonly used than gouges and v-tools, they still are handy tools to have in your tool kit. Also commonly found in palm and mallet versions.
Short bent and long bent are terms that are applied to gouges, v-tools, chisels, and skews. typically more so with longer mallet tools but can be seen in palm tools as well. Short bent tools will have a tight bend at the end of the shaft of the tool allowing you to hold the handle up high and get the cutting edge down into the wood. This is useful in relief carving and anywhere you need to carve depth. A long bent tool will have a shallower sweeping bend running the entire length of the shaft of the tool. This is useful for hollowing out projects that don't require the extra depth that the short bent tool offers.
These are some of the major types of woodcarving tools that are commonly in use today and a basic understanding of them will help you in finding the right tool for the right job.