# Animation Basics

Here we will learn how to be able to use the play button at the bottom left of the Houdini window. This will allow us to make animations.

You can press play or get used to use the arrow keys to play and manipulate the frame number.

and it is an integer. Optionally one can use $FF as a float to make sub frame computations but we don’t need that right now. Another important character is # $T

which gives you the times passed in seconds as a float. For Consistency use $F if you want the program to run equally on every computer. $T on the other hand is useful for real time applications.

Lets see what $F does with a simple example. Create a geometry node and throw in a test geometry and add a transform node to it. Transform nodes handle rotation, translation, scaling etc. Now go to the transform node and insert $F into the final entry of the rotation line. Then click on the scene and hit play. With every frame update, the transform node will rerun with the new frame number it its rotational component.