Creating Standard ACLs

Router(config)#access-list 10 permit 172.16.0.0 0.0.255.255	Read this line to say: All packets with a source IP address of 172.16.x.x will be permitted to continue through the internetwork
access-list	ACL command
10	Arbitrary number between 1 and 99, designating this as a standard IP ACL
permit	Packets that match this statement will be allowed to continue
172.16.0.0	Source IP address to be compared to
0.0.255.255	Wildcard mask
Router(config)#access-list 10 deny host 172.17.0.1	Read this line to say: All packets with a source IP address of 172.17.0.1 will be dropped and discarded
access-list	ACL command
10	Number between 1 and 99, designating this as a standard IP ACL
deny	Packets that match this statement will be dropped and discarded
host	Keyword
172.17.0.1	Specific host address
Router(config)#access-list 10 permit any	Read this line to say: All packets with any source IP address will be permitted to continue through the internetwork
access-list	ACL command
10	Number between 1 and 99, designating this as a standard IP ACL
permit	Packets that match this statement will be allowed to continue
any	Keyword to mean all IP addresses

Tip:

There is an implicit deny statement that is hard coded into every ACL. You cannot see it, but it states "deny everything not already permitted." This is always the last line of any ACL. If you want to defeat this implicit deny, put a permit any statement in your standard ACLs or permit ip any any in your extended ACLs as the last line.