1st _ Lan (Local Area Network) : 
the Local Area Network its its covering asmall physical area like company ore home or use small grouping in the building and this Lan  its too speed its between 10Mb or 100Mb or 1000Mb or 10Gb and the destance about it 1 k.m .. 
2st _ Man (metropolitan area network) :
the metropolitan area network is larger than Lan it can be in the city or in the larg places and the metropolitan  area network is interconnects a number of Lans by using abackbone cables but the destance abot man can be 1-10 k.m and MANs can also depend on communications channels of moderate-to-high data  rates. A MAN might be owned and operated by a single organization, but  it usually will be used by many individuals and organizations. MANs  might also be owned and operated as public utilities. They will often  provide means for internetworking of Local Networks for example google company !
 3rd _ Wan (Wide Area Network) :
the Wide Area Network meaning its broad area and its contains alot of Networks connected to each other hmm so we can called the internet is Wan .. ya you can say the internet is the Wan Network ...
