The var keyword is, in my opinion, bested used in the situations for which it was original introduced--LINQ queries. In these queries, the type of the returned result often has some big convoluted name that is difficult to determine ahead of time and doesn't aid the reader's understanding of what your code does.

However, doing var text = "Some text " + variableName + "some more text." is just lazy.

The var keyword is, in my opinion, bested used in the situations for which it was original introduced--LINQ queries. In these queries, the type of the returned result often has some big convoluted name that is difficult to determine ahead of time and doesn't aid the reader's understanding of what your code does.

However, doing var text = "Some text " + variableName + "some more text." is just lazy.

EDIT: @Jorg You jumped on a purposefully simplistic answer but added nothing to the discussion. OK, how about this for a better example: var items = doc.DocumentElement.FirstChild.ChildNodes; If you can figure out the type from that I'll give you a cookie.