Temperature is one of the most important parameters in about every process. It is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot. Quantitatively, temperature is measured with thermometers, which may be calibrated to a variety of temperature scales.

Temperature scales
Worldwide the majority uses the Celsius scale (°C) for most temperature measurements. It has the same incremental scaling as the Kelvin scale used by scientists, but fixes its null point, at 0°C = 273.15K, the freezing point of water. A few countries, most notably the United States, use the Fahrenheit scale for common purposes, a historical scale on which water freezes at 32 °F and boils at 212 °F.

For practical purposes of scientific temperature measurement, the International System of Units (SI) defines a scale and unit for the thermodynamic temperature by using the easily reproducible temperature of the triple point of water as a second reference point. For historical reasons, the triple point is fixed at 273.16 units of the measurement increment, which has been named the kelvin in honor of the Scottish physicist who first defined the scale. The unit symbol of the kelvin is K.

Thermodynamics
Temperature is one of the principal properties studied in the field of thermodynamics. Particularly important in this field are the differences in temperature between regions of matter, because such differences are the driving force for heat,[1] which is the transfer of thermal energy. Spontaneously, heat flows only from regions of higher temperature to regions of lower temperature. If no heat is transferred between two objects, the objects have the same temperature.
Source: Wikipedia

Temperature in the paint and coatings industry
In the paint and coatings industry there are many examples and applications where temperature plays a key role.To name a few:

DewPoint Temperature related to surface temperature during pre-treatment and paint application.

Baking temperature of thermosetting (powder) coatings.

Air temperature during application of more or less any type of coatings and water based coatings in particular.

Profiling of oven temperatures in finishing lines.

Viscosity and flow characteristics from liquid paint.

Coating temperature during application and storage.

Etc....

For some applications single spot measurements are sufficient. Other situations require a complete temperature registration during the entire production process.

Many different methods and instruments are available varying from simple bi-metal thermometers, contact- or non contact (infrared) meters to advanced thermo graphic cameras or sophisticated dataloggers.