Different welding types

[chem51]

Why are there anyway different types of welding?
Just need to know the basics only, means to understand the reasons of having those many, their shortcomings and advantages.
A chemical engineer on the round to the workshops.

[ben]

Many different uses with all these different welding types, in short.
Say for accurate, penetrated welds, gas tungsten is the one preferable.
Stick welding is used anywhere any day.
Then the materials which are being welded, so all many factors to consider.