Static IP addresses do not change, but are fixed for the life of an Internet service contract. Static IP addresses are typically found on high-volume commercial Internet connections. Most ISP's charge a premium monthly fee if you opt to have a static IP address. We have seen some company's charge $50 a month extra.
Dynamic IP addresses, however, change over time. Dynamic IP addresses are found on dial-up account, DSL, Cable, Satellite, Wireless, and many lower cost Broadband connections. They keep costs down by using a pool of IP addresses much smaller than their actual userbase.