“Spirometry is an answer to a question”
The history of pulmonary function testing is a reflection of our understanding of the functioning of the respiratory system over the years. Our first stint with spirometry in the 70s was in the form of a huge drum submerged within water. It was a formidable sight, and the whole generation probably carried the awe and discomfort throughout their lifespan. The next generation witnessed the advent of computer-based spirometry in a handy set. However, the chief obstacle in popular acceptance persisted as effort dependence and variability of output. The current generation has been able to overcome the obstacles with impulse oximetry (does not need maximal effort), fractional exhaled nitric oxide (FeNO), and others. Still, spirometry remains underperformed and underutilized in our daily practice.
Pulmonary function test (PFT) is an elaborate and composite exercise. Office spirometry is the most common practiced version and apart from its clinical and epidemiological application is an academic exercise in itself. Interpretation needs thorough understanding of respiratory physiology as also reference values and interpretative standards. 
The technical parameters and quality control are of paramount importance in appropriate utilization of PFTs.
Pulmonary function test is an execution of our understanding of respiratory physiology. Spirometry is an answer to a question. Quality control and infection-control measures are of paramount importance. Office spirometry, impulse oscillometry, and other parameters such as FeNO, DLCO, and body plethysmography are complementary to each other. PFT is yet to get proper recognition in clinical medicine.