as title. and how is it different from PF_INET ?

also, any one knows sin_family , sin_port , sin_addr ..etc ? why are they called 'sin' ?

finally, htons() host to network short , htonl() host to network long , ntohs() network to host short , ntohl() network to host long. why would programmers care about 'short' or 'long' here ? why not just use either one of them ?