In the world of men’s tailored clothing you have three basic options: off the rack, made to measure (a.k.a. custom) and bespoke. Of the three, off the rack (a.k.a. OTR) is the most ubiquitous.
Off the rack clothes are machine made, mass produced, and vary widely in terms of quality and standards. You will pay a premium for a suit by a big-name designer despite the fact that it takes the same amount of time for the machine to make a designer suit than a no-name label.
Sizes are standardized and unless you can find a brand that nails or gets very close to the fit you prefer, you should plan to invest some money with your tailor.
The good? Off the rack is widely available – just go to the mall – and generally affordable.
The bad? Since off the rack clothing is designed for the mass market, one size does not fit all. You also have a limited choice with regard to quality, fabrics, and construction.