An eraser is a piece of soft rubber or plastic that is used to rub out mistakes you make with lead pencil.
Scientific name: lawsonia inermis
A landscape is a wide view of scenery that is generally farmland or wilderness, not a cityscape. Paintings of landscapes are generally done with the paper or canvas wider than it is tall, which has given rise to the name landscape for any paper in the same format.
The opposite of landscape is portrait.
A marker, marking pen, felt-tip pen or branded as a Texta or Sharpie in some countries, is something you use to draw or write with.
Markers have their own source of ink, and a soft tip. There are lots of different kinds of marker, for writing on whiteboards, overhead transparencies, paper, glass, and of course permanent markers versus erasable markers.
An outline is a type of drawing where thin lines are used to define the edges of what you are drawing a picture of. Artists often start a picture by drawing the outline in lead pencil, and then coloring or shading it in.
An outline is also the way of describing an event or situation by giving only the most essential details, as in "here's an outline for Monday's telecast".