Short answers, pulled from the story.
A hoe is an ancient hand tool used to shape soil, remove weeds, clear old roots and crop residues, and harvest root crops such as potatoes. Specific uses include piling soil around plant bases, digging narrow furrows for seeds or bulbs, and agitating the soil surface to disrupt weed growth.
The two general types are draw hoes and scuffle hoes. Draw hoes have a blade set at roughly a right angle to the shaft and are pulled toward the user to shape or move soil. Scuffle hoes are designed to scrape and loosen the top few centimetres of soil and cut weed roots just below the surface.
In Sumerian mythology, the invention of the hoe was credited to Enlil, the chief of the council of gods. The hoe also features in a Sumerian disputation poem called the Debate between the hoe and the plough, dating to the 3rd millennium BC, in which the hoe is declared the winner.
California banned the short-handled hoe under state law in 1975 after the California Supreme Court declared it an unsafe hand tool. Long-term use required workers to bend from the waist, causing permanent, crippling lower back pain. The campaign was led by César Chávez with political support from Governor Jerry Brown.
The collinear hoe was designed by Eliot Coleman in the late 1980s. It has a narrow, razor-sharp blade that skims just under the soil surface in a sweeping motion to slice weed roots; it is unsuitable for chopping or moving soil.
Over the past fifteen to twenty years, hoes have become standard tools on large open-area archaeological excavations. They move faster than a trowel and produce a cleaner surface than mechanical excavation, making them well suited for clearing broad horizontal areas; many sites have replaced kneeling archaeologists with trowels with stooping archaeologists using hoes.