Half marathons are 13.1 miles, instead of 26.2 miles, like a full marathon. Many people who are new to running start with smaller races, like the 5k and 10k first, before moving up to a half marathon.
There are several differences between a half and full marathon beyond the obvious length of the course.
First, it requires a great leap of endurance to jump from say, a 10k, to a half marathon. While it might seem like the next natural step in a progressively more challenging ladder of physical activity, the difference between the 10k and half marathon is best thought of in terms of logarithmic difference, where one step is an order of magnitude more difficult.
That said, not all half marathons are created equal, since some will be over flatter terrain than others, while a different race might be run in a tropical climate, or at a higher altitude. Each variable: weather, terrain, altitude, all contribute to the overall difficulty level of a race.
You will need to focus more on hydration when running a half marathon, and time your fluid intake wisely. As well, eating before a race may involve an equal amount of protein and carbs, to give you long-term energy needed.
Finally, the half-marathon will typically bring out more competitive runners than a neighborhood 10k, so bear i nmind that many of your competitors will be interested in winning, rather than just finishing, or finding a nice way to get new photos for their Facebook page.