Several widgets (for example, Chart Visualizations) have special menus on them (hover over them with the mouse on the top right corner of the widget itself, and you will see the menu).

It contains the following options (from left to right):

• Download plot as PNG
• Zoom (by selection)
• Pan
• Zoom in
• Zoom out
• Autoscale
• Reset Axis to initial value
• Toggle spike lines (helps to see the values)
• Show closest data on hover
• Compare data on hover 

The most useful one is the first one (marked with an arrow), which is Download plot as PNG:

Sometimes, there is a need to embed a visualization (widget) in an external website, and still keep it refreshed when the data source changes. Redash allows you to do just that.

On the bottom left menu, click on the <>Embed button. A dialog will pop up, with the visualization already appended inside an iframe, which can be embedded in any web page you wish (you just need to copy the popped up code, and paste it into your destination website):