By Louis Jones 
An illustration can be defined as a painting, printed work or drawing used to explain, illuminate, clarify, represent or decorate a written text. Even so, illustrators sometimes use their skills to communicate through illustrations without the need for words.
In ancient times, before the discovery of photography, illustration was one of the main methods of communication. These illustrations needed to be as realistic as possible to be able to convey the right message.
Today, illustrations are used to convey messages and mood of the artist. There are numerous types of illustrations categorized based on the techniques used to create them.
Woodcutting illustrations
Woodcutting is an old technique used in ancient manuscripts. It was most popular in the middle ages as the illustrative method of choice after the printing press was discovered. These types of illustrations were popular in feudal Japan.
This technique employs the use of contrasting colours and big strokes. Many contemporary illustrators still prefer this method. It allows them to create pieces with textured looks and rougher feels.
Charcoal illustration
Commonly confused for pencil illustrations, charcoal illustrations are not as smooth as the pencil or pen illustrations. However, they are a preferred choice for artists looking to illustrate short stories, nooks and fast sketches. The blend-ability of charcoal enables the artist to use it to create a wide range of textures to represent an array of shadows, materials, objects and people. Tissues and fingers are used for smudging, blending the material and also to create soft and smooth shadows.
It is easy to differentiate between charcoal illustrations and pencil ones by looking at the thickness of the lines. Charcoal illustrations have thicker, darker and softer line quality.
Pencil illustration
The pencil style of illustrating is probably one of the most popular in modern-day. The pencil is a rich material that enables an illustrator to show transitions, soft shadows and at the same time, create accurate lines and shapes. Some illustrators use the pencil to sketch their work and later finish off the piece using another material.
Pencil illustrations can be created into monochromes, coloured art pieces, and also into sketchy, rough and dynamic pieces.
Watercolour illustration
Colour pigments are used to create varied transparencies and nuances through the addition of water to the colour pigments. The final product is a soft, airy piece with a log of depth. This method of illustration is preferred when creating art to depict a kitchen setup, femininity, and fashion. Watercolour illustration technique is one of the easiest ways of merging colours and creating colour splashes.
Lithography
Lithography is a word derived from the word stone in Greek. Originally, lithography illustrations consisted of oil, fat or wax images transferred onto a smooth lithographic limestone plate. Today, a lot of artists prefer to use offset lithography in their art. This form of illustration has become common since the advent of print press in the 1960s.
Gouache illustrations
These types of illustrations are closely related to watercolour illustrations but have been modified to make them opaque. Gouache offers thicker, rich and darker shades as compared to watercolours. They can be reworked after some years. Commercial artists make use of the Gouache technique for the creation of posters, comics, and other design jobs.
This method is particularly ideal when used as poster paint. This is because the layers of paint dry faster and completely due to the quick evaporation of the water.
Collage illustration
This is a gluing technique. Collage illustrations are made from assembling different shapes from different materials to create one piece. This method has become increasingly popular in modern-day and is believed to inspire the trend-material design.
Acrylic illustration
This is an illustration method mostly preferred by new artists. It is an easy method to work with as opposed to using oils and watercolours. With acrylics, the artist can achieve the same effects as with the use of oils and watercolours. Acrylics can be used to paint over any surface and are water-resistant once dry. Acrylics are versatile and are available in metallic and fluorescent effects.