Welding in its most basic form is simply heating two materials until they melt together, usually adding a bit of extra metal to make the joint stronger.
The most common type of welding is arc welding, which uses a small electric arc to generate the heat for melting the metals. And there are three main types of Arc welding, MIG, TIG, and Stick. While each one is different, they all use an electrode (to generate the arc), a filler metal (to create the weld bead) and something to ‘shield’ the weld from being contaminated by oxygen.
Stick welding (also called SMAW, or Shielded Metal Arc Welding), uses consumable metal “sticks” as the eletrode, filler metal, and shielding all in one. They look like a metal rod about a foot long, covered in a hard compound. The metal rod strikes the arc and melts into the weld, while the compound melts to cover the weld.
MIG (Metal Inert Gas) welding (or GMAW, Gas Metal Arc Welding), is somewhat similar to Stick in that the metal is both the electrode and the filler. Only instead of rods that need to be replaced a spool of wire is used, so it can be continually fed into the weld. A gas is used to shield the weld, usually either pure Argon or a mix of Argon and CO2.
TIG (Tungsten Inert Gas) welding (or GTAW, Gas Tungsten Arc Welding) is quite a bit different from the other two, in that you use a tungsten electrode (regardless of what metal you’re welding), and a separate metal rod that you manually feed I to the weld to make the bead. You also usually control the power of the arc with a foot pedal, meaning you’ll be using both hands and one foot, meaning you need some good coordination to do this kind of welding. It also uses sheilding gas like MIG welding, which is also usually Argon or a mix, although Helium used to be widely used.