How to specify size of image in LaTeX

An image is inserted into a LaTeX document using the includegraphics command. The size of the image can be specified in a variety of techniques:

• Specify height or width or both in terms of cm:

width=5cm

height=3cm

width=3cm, height=10cm

• Specify width as fraction of width of text column:

width=0.9\linewidth

width=0.7\textwidth

• Specify scale of image:

scale=0.5

Tried with: Ubuntu 14.04