A diagram explaining simple client-server application. At the centre, there is a cloud shape, with 2 arrows, both sides, coming in and out of the cloud. From the left-hand side, there is a box, with the text inside: client (browser). The two arrows then link the box to the cloud. The top arrow goes away from the box, into the cloud, and the arrow beneath points away from the cloud into the box. On the right-hand side of the cloud, this is similar with the same style of box but with the following text inside: server application (book catalogue, pricing and stock). The top arrows either side of the cloud are labelled book information requests and the bottom arrows are labelled book lists and descriptions. Below the cloud, there is a double-ended, dashed-line arrow that runs horizontally, labelled network. On the left, the arrow points towards a box with the text: user’s own machine, and on the right the arrow points towards a box labelled: company’s server machine.