In this example, we used two buffers (one for color and one for position). Instead, we could have used just a single buffer and combined all of the data. In general, it is possible to combine the data for multiple attributes into a single buffer. The data for multiple attributes can be interleaved within an array, so that all of the data for a given vertex is grouped together within the buffer. Doing so just requires careful use of the stride argument to glVertexAttribPointer or glBindVertexBuffer. Take a look at the documentation for full details (http://www.opengl.org/sdk/docs/man).

The decision about when to use interleaved arrays and when to use separate arrays is highly dependent on the situation. Interleaved arrays may bring better results due to the fact that data is accessed together and resides closer in memory (so-called locality of reference), resulting in better caching performance.