Much of the information you need to source and save in a worksheet will be confidential: budgets, expenses, salaries, sales projections, etc. Some of this data will no doubt be shared, too, as most organisations share sensitive data amongst different department. It's a good idea to protect this type of data so that only authorised people can access it. Even if you need them to be able to manipulate only certain parts of a spreadsheet you now have the flexibility to do this.

Microsoft Excel 2010 gives you this flexibility: you can choose which content is displayed and which is protected by using layers of control. And you can manipulate several layers, or just one, depending on which information you need to keep secure. This also means you can control anything from individual cells by locking them, to password-protecting a workbook or only specific worksheets. The possibilities appear endless.

These and many more security options are controlled in Excel 2010's Trust Center. The Trust Center is the part of Excel that allows you to set security options, including document privacy and safety. Excel 2010 also boasts digital signatures and encryption which ensures added privacy and safety of your data. Data cannot be accessed without authorisation − especially useful if you use the Internet to send and share sensitive information.

Protecting your worksheet is easy if you will be familiar with using passwords across other Microsoft programs. You can access password settings on the review tab of your document. Simply click the 'Protect Sheet' button and select the check boxes for the options you want to correct. You will find a range of options here that include protecting a sheet, worksheet and even allowing access to only a specified range of options. That way you can allow colleagues to work and input data, but not to change certain areas of your workbook - unless they are privy to your password.

Passwords are a must if you are sharing your data across your organisation and especially when using the Internet. This option is available on the file tab, in the 'Save As' command. Simply click on the 'Tools' button when saving, and select 'General Options'. You will see that there are other options here such as 'Web Options' and 'Compress Pictures' that you might also require when sharing a workbook. You can input a password in the 'Password to open' or the 'Password to modify' box. Select the 'Always create back-up' check box to create a backup, or click to clear it. You can also choose the read-only check bock at this point, or again click to clear.

If you want to make your workbook read-only, then on the file tab, click 'Protect Workbook', then select 'Mark as Final'. Just remember that the 'Mark as Final' command can be turned off and on at any time by anyone - the command only disables typing, edit and proofing marks while your document is actually marked as final.

If you use add-ins in Excel, then you need to be sure that these are security protected from viruses. To set add-in security options, select the 'File' tab, then click 'Options' to see the 'Excel Options' dialog box. From here you can access the 'Trust Center'. Now you can alter the Trust Center Setting using the button to access add-ins. You will see three options to manipulate the add-ins protection level. If the add-in security options are not set to the security you need, then you can change these in the Trust Center.

The Trust Center is also where you can control and set your privacy options. These settings help protect your from phishing schemes and from accidentally accessing websites - which could potentially be embarrassing if sharing your workbook with a client, for example.

Privacy options can be accessed in the Trust Center. These options also keep you up to date with new features (see the Automatically detect installed Office applications to improve Office-com search results). Another source of virus infection can be from macros. However, if you have up-to-date antivirus software and use Office 2010's security features then you should be protected from any malicious macros. The Macro Settings in the Trust Center houses some of the options that determine how Excel handles macros.

If you find that passwords don't work within your organisation, or feel that these are too cumbersome for your needs, you can always lock and unlock worksheet cells so that changes to your data can't be made accidentally. To do this, select the cell or range you want to lock or unlock, click on the 'Home' tab and then the 'Format' button.

f you need to protect your workbook so that nobody can access you data, then you also have the option to encrypt your spreadsheet. Just remember your password (which is case sensitive)! On the 'File' tab, click the 'Protect Workbook' button. Select 'Encrypt the Password', type your password, click OK, then confirm your password. You can remove your password by going back through the 'Protect Workbook' options.

Digital signatures are one of the most common ways to add authentication to your Excel documents. Before you can add a digital signature, you need to have a digital ID or digital certificate.

To do this, click on the 'File' tab, and select the 'Protect Workbook' button. Now choose the' Add a Digital Signature' option. You will be prompted to 'Get a Digital ID' by either going via Microsoft Office Online or by creating your own ID. You can view or remove signatures by using the 'View Signatures' command in the File tab. Individual digital signatures are indicated by red text in the signature pane and a red X on the signature details dialog box.

And for those of us who prefer to be on red alert at all times, you can adjust the message bar to alert you to a potential problem. If potentially unsafe content is detected in any workbook you have open on your desktop, a security warning will appear below the ribbon allowing you to either enable the content or leave it blocked. You can easily adjust message bar security options by accessing the Trust Center and clicking on the message bar.