Double-clicking on a sheet tab allows you to give it a descriptive name. You can change the order of the worksheets by dragging their tabs.
To copy worksheets press the Ctrl key as you drag the tab. To select the same cells in consecutive worksheets, select the cells on the first worksheet, then press the Shift key and click on the tab of the last worksheet you require.
To select the same cells in worksheets that are not consecutive, press the Ctrl key as you select the tabs. When using formulas from different worksheets you need to specify which worksheet the data is in, as well as the cell address.
When the sheet name has a space, the whole name is enclosed in single quotes.