Think BEYOND Imagination

To make it a little bit more complicated, the left vector graphic is displayed as a bitmap graphic.
The original image is an Adobe Illustrator vector graphic, but these kinds of images can't be displayed directly in your browser.
An interesting combination of pixel art and vector illustration can be found at eyeport.co.uk.
Let's forget vector graphics for the moment and focus on bitmap graphics.
Pixel art is, by definition, a bitmap graphic; an image which is described with pixels.
Pixel Art
Pixel art began when the first personal computer was introduced.
Bitmap graphics don't need much computation to be displayed.
Vector graphics have to be calculated or rendered, based on mathematically described lines and curves, and then converted into a bitmap graphic, since most output devices use pixels to display images. The whole process requires a lot of computation power.
Bitmap graphics are the best option when the computation power is not very high (early computers/cell phones). This computationally friendly feature gives pixel art a sort of 'old school'/'retro' look.
Unlike vector graphics, bitmap graphics can't be scaled without loss of quality. If you want to display bitmap graphics - let's say an icon - in different sizes, for different kinds of display devices, you need to make a different version for each size. This is a major disadvantage compared to vector graphics.
You only need one icon as a vector graphic to display it on every possible scale without loss of quality.
Pixel art can be divided into two categories: isometric pixel art and non-isometric pixel art.
Isometric Pixel Art
Isometric projection is a projection which is used to represent a three-dimensional object - or objects - in two dimensions. An object is seen from above. The top, left, and right side of the object are visible.
Isometric projection lacks perspective; objects far away from the spectator have the same size as nearby objects. Isometric projection is extensively used in older computer games and contemporary pixel art, because you don't need to resize (read redraw) objects. Or in the case of computer game perspective distortion doesn't need to be calculated.
To mimic perspective, overlapping can be used as well as color: the further away from the spectator, the more the colors loose their brightness.
The x-axis and z-axis should make an angle of exactly 30 degrees with the horizon. The alignment of pixels on the screen prevents the use of exactly 30 degrees, because this angle would result in an irregular line (left image). Instead of 30 degrees, 26.56 degrees is commonly used in pixel art. Practically speaking, this results in a line that is regular; the line has two pixels per interval. This is also referred to as the 2:1 pixel pattern ratio (right image).

To build a simple object, an isometric cube can be used as fundamental building block.
The isometric cube can be made once, and then used many times by copying and pasting.
Think of Lego bricks in real life.
Drawing an Isometric Cube An isometric cube can be drawn very easily

Start with a vertical line (1). Next, draw a line parallel to the z-axis (2), previously described. Again, draw a vertical line (3). Next, draw a line parallel to the z-axis. The left side of the isometric cube appears (4).
You can repeat the described steps again on the right side, but you work more efficiently when you copy the left side of the cube and then flip the selection horizontally and paste it on the right side (5 and 6).
The last step is to draw the top of the isometric cube. Copy the diagonal lines at the top, flip the selection vertically, and paste it on top of the cube (8).
The outline of the isometric cube is finished.
You could use the outline (8) as a building block to create isometric objects, but it's more handy to add some shading first (9).
By using a shaded isometric cube, the shading needs to be done only once (and then copied many times). The creation of a simple isometric object is much easier with a shaded isometric cube, since the shap is more clear than just an outline of an isometric cube.
A Simple Isometric Object
The shape of the fundamental building block, an isometric cube, is important, since not all blocks are useful.
Like the 2:1 pixel pattern, ratio lines can be drawn best with regular intervals: two adjacent pixels, one pixel up/down, two adjacent pixels, etc.
The isometric cubes used on the left side of the image can't properly be stacked vertically; the vertical lines don't fit. By using the isometric cube on the right side of the image, the regularly shaped lines fit perfectly.

The above example shows an easy way to create a simple isometric object, with the help of one shaded isometric cube as the fundamental building block.
The appearance of the object can be adjusted to get rid of the individual building blocks (basic version). The outlines inside the isometric object are carefully removed (simplified version). Next, highlights and shadow are added (highlight version and shadow version).
By adding highlights and shadow, the shape becomes more spatial, so that it takes a spectator less energy to perceive the shape.
As the last step, an extra border can be added to separate the object from the background. There's no real reason to add an extra border, other than as a personal, subjective preference.

As you can see, it's quite easy to create a simple isometric object.
The object is simple, the complexity and/or scale can be changed, and the workflow remains the same.
An isometric cube can also be used as a reference for constructing a more complex, detailed pixel art object.
The teapot and Nintendo GameCube are made with the help of an isometric cube.

Isometric Objects with Curves
Curves are more difficult to draw, but after some practice it can be done.
Like using lines with a regular interval to make isometric pixel art, curves can be drawn following the same principle. For example, you could first use a line with three adjacent pixels, followed by two adjacent pixels and so on.

Everyone can learn the basic rules, but don't follow the rules too rigidly.
Try to practice and experiment with different angles, colors, choice of topic, etc.
Non-isometric Pixel Art
Non-isometric pixel art is pixel art that is not isometric.
The IC-Project illustration is an example of non-isometric pixel art.
Time-consuming
The number of pixels rapidly increases, even with small pixel art illustrations, which makes creating pixel art a time-consuming process.

The IC-Project illustration contains 1600 pixels horizontally and 1040 pixels vertically. The total amount of pixels equals 1.664.000 pixels (1600 x 1040 pixels).
Not every pixel is individually drawn; some areas remain white. On the other hand, not every pixel is drawn right away at the right position, and some parts of the illustration are drawn a few times before they look right (see the 'Deleted Artwork' chapter).
The actual amount of pixels drawn is probably a multiple of these 1.664.000 pixels.
The Fun of Pixel Art
You've just read that creating pixel art is a very time-consuming process, so why do it at all?
Pixel art allows you to work on a sort of molecular level of an image. You have to puzzle as to how to place a pixel at the right position; one pixel to the left or one pixel to right, or a different color of the pixel, can make a difference.