Netflix requires a broadband Internet connection.
The connection can be wireless or via Ethernet.
Unless you are planning on connecting to the Internet via the free WiFi provided by many wireless hotspots such as Starbucks, McDonald's, etc. then you need a ISP.
Streaming video, such as Netflix and Hulu require a lot of bandwidth. Here are the minimum recommendations from Netflix. https://support.netflix.com/en/node/306
Depending on your exact location, you can choose from several different types of broadband Internet access. They include DSL, cable, fiber, satellite, and wireless from a cellular provider.
DSL is generally the cheapest broadband option, however it is also usually the slowest. DSL (Digital Subscriber Line) is a form of broadband Internet that is transmitted over standard twisted pair copper telephone lines. DSL speeds range from 512 Kbps to 12 Mbps depending on distance from the telephone company and plan that you purchase. http://en.wikipedia.org/wiki/Digital_Subscriber_Line
Cable - Cable Internet is a form of broadband Internet transmitted over coaxial television cables. Cable Internet speeds range from 1 Mbps to over 300 Mbps using newer DOCSIS 3.0 technology. The speed of the service depends on your exact area and service package that you order.
Fiber - Newer fiber optic services can be as fast as 1000 Mbps, https://fiber.google.com/about/ usually transmitted on fiber optic cables and often combined with copper from the street to the house. Fiber connections can also provide on demand HD television and digital telephone service on the same line.
There are also 3G and 4G wireless mobile broadband services and satellite Internet, but these are normally only used where Cable or DSL are unavailable due to the higher cost, slower speeds and low monthly bandwidth limits.
Naturally more speed is always better, however the tradeoff is price. Internet bandwidth is shared among all devices connected to your wireless router. In simple terms, the more users and devices you have, the more speed will be required.
Many people would be likely be surprised at how many active connections their wireless router has. I have dozens, cell phones, tablets, iPods, game consoles, laptops, desktops, ROKU boxes, Internet enabled devices such as TVs and audio receivers, and the list goes on.
To compare speed and prices of your local competitors, go to a ISP comparison site that lets you input your address, and compare the pricing and terms of the offers that are available in your area. In the US you can use this one http://isp1.us/find/ otherwise do a search for "ISP comparison" at your favorite search engine.
The physical address is needed because some services, particularly DSL, are very distance sensitive. For example you might be able to get a specific level of service while your next door neighbor can't.
You'll want to pick the fastest plan that fits your budget. In some areas this can be 300 Mbps+. But these high end broadband plans are expensive. You may find that something in the 10 to 50 Mbps range might satisfy your needs at a much lower cost.
Good Luck...