The interactiveparams command is part of the plots package. It allows you to interactively adjust the value of certain variables in an expression and see the effect of plotting with these variables set to constant values.

The command produces an interactive Maplet.

For a more flexible way to create a plot with interactive parameters, see the Explore command.  Using Explore, you can create an interactive plot with sliders or animation in the worksheet.

$\mathrm{with}\left(\mathrm{plots}\right)\:$

$\mathrm{interactiveparams}\left(\mathrm{plot}\,\left[\sin \left(x+y\right)\,x=0..\mathrm{\pi }\right]\,y=-\mathrm{\pi }..\mathrm{\pi }\right)$

$\mathrm{interactiveparams}\left(\mathrm{animate}\,\left[\mathrm{plot}\,\left[x^p+t\,x=0..3\right]\,t=-5..5\right]\,p=1..5\right)$