Most of People will watch the WC on TV but those people who don't have TV may watch the Live Streaming online. there are dozens of options available to watch the Online streaming which I am going to share.
1 FIFA.com TV
Live streaming of the entire 64 matches will be available on the official website of FIFA. on website you will find option of FIFA TV where you can watch the matches.
NOS is an dutch broadcaster which will show all the matches of FIFA World Cup at http://nos.nl/wk2014/.
famous sports channel ESPN will also be telecasting the big event so you can enjoy the matches on their live streaming.
fans from UK can enjoy the Tournament on SKY's streaming.
famous media group BBC are also going to show the World Cup but to users in UK only. If you are from outside then you can use a UK proxy to watch the streaming.
so you have plenty of options available to watch the live action of FIFA World cup 2014 Live online. many Illegal streaming sites will also be out there available on Google but most of them are of poor quality.