Inkscape makes it really easy to edit paths. Just one of the reasons why Inkscape is awesome. This guide provides a quick overview of Inkscape’s path editing tool (the node tool).
There are four different kinds of nodes in Inkscape. Each node is represented by either a diamond, square, or circle (the smooth and symmetrical nodes are both square).
control click on a node to change its type, cycling through the four available options. If one of the node handles has been deleted, changing the node type will respawn the handle (but not the corner node).
See also: How to draw a flat, single color lightbulb icon in Inkscape
control click on a handle to delete it. If both nodes of a handle are deleted, it becomes a corner node.
shift click and drag outward from a node to spawn a new handle without changing the node type.
It's also possible to select node type from the top menu panel.
Use the path tool (the node tool, hit N) to drag select multiple nodes in a path:
Invert node selection with shift + !:
Add a node to a path by double clicking on the path with the path editing tool:
Delete any node by selecting it and hitting delete. When deleting a node in a path, the immediately adjacent nodes try to retain the overall shape of the path by automatically adjusting their handles. Use control + delete to delete a node without effecting the adjacent nodes.
See also: How to draw a simple 3D ruby in Inkscape using elipses, triangles, and Inkscape’s very good snapping and alignment tools