ESmol is a simple, functional molecular viewer. All of the features of the app are accessed from the menu—these include display options for both the protein and its ligands, if they are present in the structure. The protein can be displayed as a trace or ribbon, and sidechains can be visible or hidden. The ligands can be depicted using lines, sticks, or spheres. One thing that is noticeably absent from this app is a help/introduction page. Users will not know, for example, that the sample molecule that appears when the app is opened is deoxyhemoglobin; nor is it clear exactly how to display other molecules. This information is more clearly explained on the app page in the Android Market. Users can open pdb files that have been saved to the SD card in a certain directory, or pdb files can be directly downloaded from the RCSB Protein Data Bank.