Determinate tomato plants are bushy and many gardeners grow them on the ground. By growing them in cages, you can keep fruit off the ground. Indeterminate varieties have stems that grow indefinitely. They produce leaves, flower clusters, and suckers until frost, pruning or injury stops it's growth. If growing these varieties on the ground, they will take up more space then the determinate types.
Indeterminate varieties are well suited for staking.
When staking tomatoes, tie the main stem loosely to a stake. Then, remove suckers by pinching them as the plant grows. We call this pruning or suckering. If you prune a determinate type tomato, you will limit the number of flower clusters to the main stem. It is much easier to use an indeterminate variety when staking.