Linear programming involves optimizing (maximizing or minimizing) a linear objective function, subject to a set of linear constraints. The objective function typically takes the form:
\[
Z = c_1x_1 + c_2x_2 + \dots + c_nx_n,
\]
where \( c_1, c_2, \dots, c_n \) are constants and \( x_1, x_2, \dots, x_n \) are decision variables.
Final Answer:
\[
\boxed{\text{Linear function}}
\]