How can I combine cells in a row in a latex-table?

In a table I want to combine some of the columns, but not in all rows. How can I realize this with LaTeX?

From stackoverflow

• \multicolumn{<number>}{<formatting>}{<contents>}

  Where the arguments are

  1. Number of columns to merge
  2. the justification and formating string (just like you use in the table header, i.e. "|c|" or the like)
  3. The contents to put in the merged columns

  This command simply replaces the <number> columns and is used inline.

  ---

  Addition: This is also how you change the formatting of a single field in only one row of the table. Just use \multicolumn{1}{<new format>}{<contents>}.

  Mnementh : Thanks, it works fine. My first problem was, that I set as formatting only {c} and at this rows no lines were drawn. I had to change format-param to {|c|}, that worked as expected.