static i.p. address

Is it possible to have a static or fixed i.p. address? It seems almost anytime I reboot, I'm assigned a new i.p. address. Some sites I use monitor the address and if it changes, I'm blocked from logging on. Then I have to go to my email, retrieve the email that states my address changed, select the link from the email, which takes me back to the site and I have to login again. I understand it's a security feature of the site, which is fine. However, having a static i.p. would eliminate having to login multiple times.