Front, back or underneath tells you which system is leaking. Timing during the cycle narrows it further, often before you move the machine at all.
Common washer problems
All washer guides
Washing Machine Leaking: Locating It by Where the Water Appears
Washer Shakes, Bangs and Walks Across the Floor
Violent movement during spin has three usual explanations, and two of them cost nothing to fix. The third is worth catching before it damages the machine.
Water Left in the Washer: Finding What Is Blocking It
Standing water at the end of a cycle is nearly always an obstruction, not a failed pump. The drain filter is the first place to look.
Clothes Come Out Soaked: Why the Spin Never Happened
A spin cycle that never ran leaves a load dripping. Balance and drainage explain most cases, and both are things you can settle in a couple of minutes.