ANY ONE KNOW y we use the adapter to run the signal for WiFi

CAN any one about why we are using an ADAPTER for the WiFi  router
THERE are 7 reasons to use an adapter to connect the
ROUTER and WiFi transmission CablE
1.IT GIVES A FREE USAGE ANYWHERE IN SOME AREA
2. BY IT WE DON'T NEED TO INSTALL ANY HARDWARE 
3.IT WITHDRAWS THE COMPLEXITY CIRCUIT/CONNECTIONS IN OUR USAGE AREA
4.ELIMITES TO UPGRADE THE COMPUTER
5.USAGE OF AREA USING 
6.LESS CURRENT USAGE
7 ETC................