Etching (hard ground): A type of intaglio print where lines are etched into the plate. The metal plate (usually copper or zinc) is covered with an acid-resistant coating, and then using a needle tool, lines are drawn into the plate, exposing the metal. Once the drawing is complete, the plate is submersed into an acid tank (usually ferric chloride for copper plates, and nitric acid for zinc plates). In the acid, the exposed lines or areas of the plate are bitten away, while the rest of the plate remains protected by the acid-resistant coating. Once etched, the plate is printed by wiping ink into the etched areas of the plate and printing with damp paper under extreme pressure. The smooth level surface of the plate will print white, while the lines that were etched away will hold ink, and be printed onto the paper.

Aquatint: This etching technique is a tonal process used to achieve wash-like effects. Rosin or spray-paint is applied to the plate (ideally the rosin or spray-paint should have a fine even coating on the plate, about 50% coverage) to give this tonal effect. The areas that have spray paint resist the acid, and the open areas of the plate will be etched. The tonal variation is controlled by the amount of time etched in the acid: the longer the etch, the darker the aquatint will print.

Spit-bite: A direct etching method of painting acid onto an etching plate with an aquatint ground. A great variety of tones and subtleties can be achieved by varying the time and strength of the acid application.

Etching Tools
Etching needle: this tool, usually steel, has a very fine and sharp point for drawing lines through the hard-ground on a plate. By removing the hard-ground from the plate while drawing, the needle tool exposes the copper beneath the ground. When the lines are all drawn, the plate is ready to be etched.  
Burnishers (also used in mezzotint): highly polished finish tools made of high carbon tool steel, and come in a variety of sizes. The burnisher smoothes out and lightens etched areas, and polishes the plate surface. It can be used to create an image or to make corrections on the plate. The burnisher is typically used after the scraper, to finish polishing or smoothing an area of the plate.  
Scrapers (also used in mezzotint): These are trianglular shaped tools made of high carbon tool steel, and come in a variety of sizes. The three sharp edges are used to cut off or scrape away the plate surface. The scraper is used to create an image on an etched plate or to make corrections on the plate.  
The Process/Creating the plate
Hard ground etching
First the hard ground is put on the plate. Once it has dried, it is ready for an image.   Using an etching needle, the image is drawn on the plate through the hard ground, exposing the copper.   Once the drawing is finished, the plate is ready to be etched. The lines drawn into the plate will be etched, while the rest of the plate remains protected by the hard ground.
The plate is submersed into the acid tank to etch. Plates are etched for varying lengths of time.   I had this plate etch for 30 minutes. When the 30 minutes is up, the plate is taken out of the acid.   The plate is then rinsed off in the sink.
Then the hard ground is cleaned off the plate with mineral spirits.       Once the plate is clean, it is ready to be printed.
The first step to an aquatint is putting the aquatint onto the clean plate. Here, I use spray paint for the aquatint.   Once the spray paint has dried, areas that are to remain white or unetched are blocked out with asphaltum, and then the plate is ready to etch.   Once the plate has etched and been printed, corrections or adjustments can be made to the plate. Here, I am burnishing an etched aquatint plate to lighten some areas.
Spit-bite aquatint
First, the spray paint is applied to the plate in the same way as described above.   Once the spray paint has dried, acid is then applied to the plate with a brush.   This technique allows me to control where the acid is painted, which areas are painted with acid first or last, and how long to let certain areas etch.
Printing the etched plate
For this example, I show the process of printing a three plate etching.
The first plate is a hard ground line etching of a tree, printed in black. The next two plates
have both aquatint and spit-bite and are printed in red and brown.
First, the inks are mixed and prepared.   Once the ink colors are ready, they are carded onto the plate.   The entire surface of each plate gets covered with ink.
Then, using tarlatan fabric, the ink is pushed into all etched grooves.   Then, the excess ink is wiped off the surface.   The wiping stage is finished with a paper wipe, further cleaning the surface.
The same steps of inking are done for all three plates.   The first plate is registered on the press bed.   Then the paper that has been soaking
in water is blotted for printing.
Once the paper is placed over the plate, it is secured at the edge with tape, creating a hinge.   The press blankets are then placed
over paper to be printed.
Then it is run through the press.
The print is carefully lifted from the first plate, and that plate is removed from the press bed.
  The second plate is registered on the press bed, then the paper is placed back over the plate, and is again run through the press.   The last plate is registered and then printed as the first two were.
The final print is liften from the third plate.  
The final print after all three plates have been printed.