Matplotlib is a two-dimensional (2D) plotting library for Python. It was created by John D. Hunter, an American neurobiologist, and was first released in 2003. Shortly before John passed away on August 2012, the development team was led by Michael Droettboom, who was further joined by Thomas Caswell.
With Matplotlib, you can generate lines, scatter graphs, bar charts, histograms, error bars, etc, and even do simple 3D plots using the mplot3d toolkit.
Matplotlib has a module called Pyplot, which provides an interface similar to MatLab.