What does this mean: "Wi-Fi has the self-assigned IP address...& will not be able to connect to the Internet"? I have internet access but I noticed that in System Preferences/Network, although the W-Fi status is "On" this statement is below: "Wi-Fi has the self-assigned IP address XXX.XXX.X.XX and will not be able to connect to the Internet." There is a yellow dot preceding the "Wi-Fi / Self-Assigned IP" icon on the far left of the System Preferences/ Network window. The Network Diagnostics shows all the items under Network Status as green. My modem does not have a router. It is behind a Verizon (ISP) router that I do not physically own or have access to. I can only access the settings at: "my home.modem manufacturer's name.com". Is this still a problem that needs correcting? Thank you. 

UPDATE: My ISP says: "Okay that's the issue as it is a 6100 modem it does not have a feature or wireless option you need to get one wireless router from ups store...I will send you a free modem which is an advanced one.."

MacBook Pro with Retina display, OS X Mavericks (10.9.5), MacBookPro11,3; Airport Time Capsule
So there are two things happening when a wifi device wants to use "internet". First it has to join the wifi network using an AP (access point) If there is a password like WPA that needs to be supplied. Next the device needs to get an IP address. That information comes from a router. It is not always necessarily true that the router and AP are the same piece of equipment. If the IP address acquisition (typically via DHCP) fails or times out the device will assign itself an IP from 169.254.X.X. However this IP can never talk to the Internet and the device knows that so that's why the message is provided. Sometimes this is simply resolved via a reboot of the router, but it could also be a hardware failure, especially if the AP and router are two separate devices.