brush tools;

bucket fill;

The bucket fill tool fills an area (either of selection or similar colours) with a colour or pattern.

blend/gradient;

The blend/gradient tool fills an area with a gradient (of both the foreground and background colour or an existing gradient).

pencil;

The pencil tool paints hard-edged lines - not anti-aliased.

paintbrush;

The brush tool paints smooth or fuzzy-edged lines - anti-aliased or feathered.

eraser;

The eraser tool erases pixels from a layer

airbrush;

The airbrush tool is a paint tool with variable pressure (pressure can vary).

ink;

The ink tool paints anti-aliased lines (with a simulation of a nib).

clone;

The clone tool copies pixel from one part of an image to another.

heal;

The heal tool heals irregularities in an image.

perspective clone;

The perspective clone tool allows you to clone a part of an image according to the perspective you want.

blur/sharpen;

The blur or sharpen tool can blur or sharpen an image, alternatively.

smudge;

The smudge tool spreads pixels in a specific direction.

dodge/burn;

The dodge or burn tool lightens or darkens an image's shadows, mid tones or highlights.

selection tools;

rectangle selection;

The rectangle selection selects a rectangular or square area/region of an image.

ellipse selection;

The ellipse selection selects a circular or elliptical area/region of an image.

free selection/lasso;

The free selection or lasso tool draws free-form selections.

fuzzy selection/magic wand;

The fuzzy selection or magic wand selects regions with the same/similar colours, that are next to each other.

by colour;

Just like the magic wand, the by colour tool selects the same/similar colours, all over the image, regardless of whether they are next to each other or not.

scissors;

The scissors tool is used to select shapes, by means of path. (similar to the path tool and lasso)

foreground select;

The foreground select tool allows you to extract foreground (or portion of image) from an active layer.

other tools;

path;

The path tool allows selecting and modifying paths.

colour picker;

The colour picker selects the colour of a pixel and sets it as either foreground/background colour.

magnify;

The magnify tool alters the zoom level of an image.

measure;

The measure tool shows distances and angles.

text;

The text tool inserts text into your image.

transform tools;

move;

The move tool moves layers and selections.

align;

The align tool aligns or arranges layers and/or other objects.

crop;

The crop tool crops or clips the image/canvas.

rotate;

The rotate tool rotates the active layer, selection or path.

scale;

The scale tool scales (changes the size of) the active layer, selection or path.

shear;

The shear tool shifts part of the image to another direction.

perspective;

The perspective tool changes the perspective of the active layer, selection or path.

flip;

The flip tool flips layers and selections.