This link on a LifeHacker VPN story is a little old but definitely worth a look. VPN stands for Virtual Private Network and is what many companies use to allow employees to work from home. VPN software creates a secure encrypted tunnel between a machine and another network. For the longest time, this was only available to big companies.
However, now there are a lot more affordable private options anyone can use. The article gives a detailed explanation of the what and why. In addition, it includes a list of several vendors offering affordable service options.