Illustrator - Glossary

Artboard: Canvas in illustrator; workspace
Area Graph Tool: A helpful tool in making a graph conform to a certain area size. In rectangular form, users can specify the area's height and width as well as the graph data.
Arc Tool: Allows the user to make open or closed arcs with the ease of drawing a line segment or polygon. Options including the arc's size and slope are customizable.
Arc Upper: A warp effect that curves the top edge of an object and allows for horizontal or vertical distortion throughout.
Pen Tool: A tool that creates paths made up of points, lines, gradients, and solid shapes.
Blob Brush Tool: A drawing tool that acts like a brush but creates closed filled paths instead of strokes.
Direct Selection Tool: Selects, paths, shapes points, lines, and gradients.
Hand tool: A tool to help navigate around artboard.
Line tool: A tool to simply create a line
Rectangle tool: A tool to simply create a rectangle
Rounded rectangle tool: another tool to create rectangles yet, this one has curved corners.
Brushes Panel: A commonly used panel to add various styles to stroked paths. You can create new brushes in assorted styles (calligraphic, artistic, etc), edit existing brushes, go through downloaded libraries of brushes, and set up your preset brush gallery so it's on hand whenever you need it.
Join Tool
The join tool allows you to take two paths and join them together to create one single path. With the join tool selected, just click and drag a circle around the two end points of the path you want to be connected, and Illustrator will join them together for you.
ReShape Tool
Allows to select more than one point on existing path and move them in the same direction
Shear Tool
Allows you to skew proportions on existing path
Twirl Tool
Allows you to create twirls on existing path
Rotate Tool
Allows you to rotate path
Reflect Tool
Allow you to reflect path
Ellipse Tool
Creating elipses and circles. For perfect circles, shift is held down.
Flare Tool - creates lens flares. i.e. gradients that create tahe look of one.
Polygon Tool - any size shape a polygon


SOURCE:
https://design.tutsplus.com/articles/the-a-to-z-of-adobe-illustrator--vector-20799