There are 3 main uses for the static.
1. If you declare within a function:
It retains the value between function calls

2.If it is declared for a function name:
By default function is extern..so it will be visible from other files. if the function declaration is as static, it is invisible for the outer files

3.Static for global variables:
By default we can use the global variables from outside files If it is static global..that variable is limitied to with in the file

No.  The signature of the virtual method must remain the same.  (Note: Only the keyword virtual is changed to keyword override)

A static or dynamic object contained in a Web application that can be referenced by a URL.

They become class properties.

A set of standards that includes specifications for embedding SQL statements in methods in the Java programming language and specifications for calling Java static methods as SQL stored procedures and user-defined functions. An SQL checker can detect errors in static SQL statements at program development time, rather than at execution time as with a JDBC driver.

A delegate in C# is like a function pointer in C or C++. A delegate is a variable that calls a method indirectly, without knowing its name. Delegates can point to static or/and member functions. It is also possible to use a multicast delegate to point to multiple functions.