query regarding asp.net

U may have seen in the forms like that of companies n all which consist of all the things how they are made any idea?How can i get this thing...

For all country you can get by code. but for state and city you have to manually insert
in to data base.

or you can buy the data base of it

Bro this is specific and not for all countries in the world i want that it shows all the countries their state and cites this one i know.If u have any idea how to design it please let me know.
And thanx 4 this reply...

Refer to this link:

http://aspsnippets.com/Articles/Cascading-DropDownList-for-CountryStateCity-in-ASPNet.aspx

http://www.c-sharpcorner.com/uploadfile/rohatash/dropdownlist-with-country-state-and-city-in-asp-net/