It works like this: You have a wireless access point for your computer to connect to the Internet. If you do not set a password on that wireless connection, then anyone with a wireless device can connect to it and use your Internet connection. That means a person who enjoys child-pr0nography can use your Internet connection, and then you get arrested for it. And yes, I misspelled pr0n on purpose because I don’t want that word on my website.
Watch the MSNBC video and see how it happened to one innocent person. Luckily, the authorities figured out what really happened. But still, getting arrested in your place of business is exceptionally inconvenient, even if you are completely innocent. Security is always important. Please consult your IT professional about your security and remain vigilant.