Hemp is a strong, fibrous plant that can be used to produce durable fibers.
Hemp seeds can drop from tall grass, which makes it one of the easiest crops to get in early-game.
Hemp can be crafted into fiber based items, such as twine and durable fiber. It is also possible to directly turn hemp into hemp seeds, allowing for regrowth and the production of hemp oil. It should be noted that these recipes may be inaccurate in terms of yields, have someone confirm this.
Using a millstone will result in better yields of fibers, as shown below:
Hemp grows in 5 stages, and after that, grows one block taller, in one stage. Because of this, it is much more profitable to only harvest the upper part of the plant. This is because destroying both block requires the seedling to undergo the first four stages before any hemp can be harvested, but harvesting just the first block lets the plant grow back in a very short time, resulting in more hemp in the long run.