To insert a new drawing select Drawing from the Insert menu and a new window pops-up over the document (see left). This is the same for all application types.
You are then free to draw using any combination of lines (both straight and free form), text and a series of predefined shapes (see below). You can do all the sorts of things that you would expect to be able to do such as change the colour of the text, fill objects etc. and that’s about your lot.
The drawing works well and allows plenty of scope for simple diagrams such as flowcharts, organisation charts and relationship diagrams and the like.
There are one or two minor niggles. Firstly while there is a snap to grid option there isn’t the same for snap to object so when connecting boxes with lines if you move an object connected objects don’t move as well. The other problem is that the drawing didn’t seem to work offline. Normally when offline options that are not available are greyed out but Drawing wasn’t so I clicked it and got the page not found message below. So I am not sure whether this is supposed to be available or not.
If you are looking for something more sophisticated then take a look at DrawAnywhere. This is much more like Visio in it’s capabilities offering many more objects and has the snap to object that Google is currently missing. However, other online drawing services should be worried as it is obviously easier to include a Google Drawing into a Google Doc.