Most people buying their first welder get stuck at the same fork in the road: MIG, TIG or MMA. Each process strikes an arc differently and suits a different type of work, so the right choice depends more on what you'll be building than on which machine looks the most impressive on a shelf.
Plasma cutting uses a jet of ionised gas, usually compressed air, forced through a nozzle at high speed and heated by an electric arc to a temperature hot enough to melt through electrically conductive metal. The molten material is then blown clear by the same jet, leaving a narrow, clean cut. Unlike oxy-fuel cutting, plasma works on any conductive metal, including stainless steel and aluminium, not just carbon steel. Hypertherm is the plasma cutting brand we get asked about most, and it's worth understanding the basics before comparing specific units.
If you're still working out which process fits your workload, it helps to talk it through with people who field these questions every day rather than guess from a spec sheet, and the team behind https://asteroidsathome.net/boinc/view_profile.php?userid=1303843 in Thirsk deal with exactly this kind of query on the advice line.
TIG welding relies on a handful of small consumable parts inside the torch that have an outsized effect on how the arc behaves. The tungsten electrode itself doesn't melt into the weld; it simply carries the arc, and different tungsten types, distinguished by their alloying elements, suit different current types and materials. Getting the wrong tungsten for the job typically shows up as arc wander or poor arc starts long before it shows up anywhere else.
The figure changes with output. Turn the amperage down and the duty cycle climbs, because the internal components are working less hard. This is why a welder can feel completely different in a busy production environment compared with occasional home workshop use: someone welding continuously through a shift needs a much higher duty cycle at their working amperage than someone doing short repair jobs a few times a week. It's the kind of spec worth comparing properly across brands such as Kemppi and EWM, not just reading off the headline amperage figure.
Duty cycle is one of the most misunderstood figures on a welder's spec sheet, yet it tells you more about real-world usability than the headline amperage does. It's expressed as a percentage over a ten-minute period at a given output, so a machine rated at 30% duty cycle at its maximum amperage can run for three minutes out of every ten at that setting before it needs to rest and cool.