acces list for use the perticular using the acess network

Access lists controls the traffic flow between the routers 
its a layer three security and is also called as packet 
filtering firewall 
Access lists are of three types
1.Standard access list
2.Extended access list
3.Named access list

1.standard access list : 

acl no lies between 1-99
Let us say two routers are there and you want to block 
packets from a network or a host or from a particular 
subnet it can be impelemented using standard access list 
but the disadvantage is at the same time even you are 
unable to send the data to that particular network or to 
host or to that subnet ,..means two way communication is 
stopped and it is to be implemented at your end means at 
destination end 

2.Extended access List :

acl no lies between 100- 199
Extended access list also same as stnadard acl 
except ..only one way communication is stopped means 
evanthough you are unable to receive the packets from 
paticular source you can send the packets to that 
particular source and one more major diff is it is 
implemented at the source end and one more advantage 
is we can block particular services like http.ftp,snmp etc 

Sorry i dont know much abt named access list :)