How do I save my computer from crackers?

Answer:
- Make sure you are behind a properly configured firewall.
- Use a secure operating system, such as Linux, or if you must use Windows make sure that you have anti-virus and anti-malware programs and that they are up to date.
- Keep up to date with system patches.
- Use strong passwords and don't tell them to anyone (and don't put them on a post-it note attached to your monitor).
- Try not to use the same password for different services.
- Don't run unknown programs or visit untrusted websites.
- Beware of email attachments (even from friends) and emails that claim you need to log in to your bank/paypal/ebay/etc. account. If you suspect an email may be fake, type the address into your browser manually, DO NOT click on the link provided.
First answer by Robogymnast. Last edit by Robogymnast. Contributor trust: 65 [recommend contributor recommended]. Question popularity: 2 [recommend question].