6 mil polyethylene plastic sheet as vapor barrier in construction
Plastic film is a thin continuous polymeric material. Thicker plastic material is often called a "sheet". These thin plastic membranes are used to separate areas or volumes, to hold items, to act as barriers, or as printable surfaces.
Plastic films are used in a wide variety of applications. These include:
packaging, plastic bags, labels, building construction, landscaping, electrical fabrication, photographic film, film stock for movies, video tape, etc.
Almost all plastics can be formed into a thin film. Some of the primary ones are:
A tube of extruded film being blown to expand
Plastic films are usually
thermoplastics and are formed by melting for forming the film.  Cast -
Plastics extrusion can cast film which is cooled or quenched then wound up on a roll.
Extruded film can be stretched, thinned, or oriented in one or two directions. Blown or tubular process forces air into an extruded ring to expand the film. Flat tenter frames stretch the extruded film before annealing. 
Calender rolls can be used to form film from hot polymers  Solution deposition is another film forming process.
Skiving is used to scrape off a film from a solid core (sometimes used to make PTFE
thread seal tape) Coextrusion involves extruding two or more layers of dissimilar polymers into a single film
Lamination combines two or more films (or other materials) into a sandwich.  Extrusion coating is used to form a film onto another film or substrate
Plastic films are typically formed into rolls by
roll slitting. Often additional coating or printing operations are also used.
Films can be modified by physical vapor deposition to make metallised films. Films can be subjected to corona treatment or Plasma processing; films can have release agents applied as needed.
Ammala, Anne (2011). "An overview of degradable and biodegradable polyolefins". Progress in Polymer Science. 36 (8): 1015-1049. doi: 10.1016/j.progpolymsci.2010.12.002 . Retrieved 2018.
White, James Lindsay (July 20, 1990). . Wiley-Interscience. p. 49 Principles of Polymer Engineering Rheology . Retrieved .
US 5072493 A, Hommes, "Apparatus for drawing plastic film in a tenter frame", published 1991
US5167894A, Wilfried W. Baumgarten, "Apparatus comprising an extruder and a calender for producing sheets and/or foils from plastic or rubber mixtures", published 1992
US5037683A, Schirmer, "High strength laminated film for chub packaging", published 1991 D882 - Standard Test Method for Tensile Properties of Thin Plastic Sheeting
D1004 - Standard Test Method for Tear Resistance (Graves Tear) of Plastic Film and Sheeting
D1204 - Standard Test Method for Linear Dimensional Changes of Nonrigid Thermoplastic Sheeting or Film at Elevated Temperature
D1593 - Standard Specification for Nonrigid Vinyl Chloride Plastic Film and Sheeting
D1709 - Standard Test Methods for Impact Resistance of Plastic Film by the Free Falling Dart Method
D1894 - Standard Test Method for Static and Kinetic Coefficients of Friction of Plastic Film and Sheeting
D1922 - Standard Test Method for Propagation Tear Resistance of Plastic Film and Thin Sheeting by Pendulum Method
D1938 - Standard Test Method for Tear Propagation Resistance of Plastic Film and Thin Sheeting by a Single Tear Method
D2103 - Standard Specification for Polyethylene Film and Sheeting
D2582 - Standard Test Method for Puncture Propagation Tear Resistance of Plastic Film and Thin Sheeting
D2673 - Standard Specification for Oriented Polypropylene Film
D2732 - Standard Test Method for Unrestrained Linear Thermal Shrinkage of Plastic Film and Sheeting
D2838 -Standard Test Method for Shrink Tension and Orientation Release Stress of Plastic Film and Thin Sheeting
D2923 - Standard Test Method for Rigidity of Polyolefin Film and Sheeting
D3420 - Standard Test Method for Pendulum Impact Resistance of Plastic Film
D3595 - Standard Specification for Polychlorotrifluoroethylene (PCTFE) Extruded Plastic Sheet and Film
D3664 - Standard Specification for Biaxially Oriented Polymeric Resin Film for Capacitors in Electrical Equipment
D3985 - Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using a Coulometric Sensor
D4321 - Standard Test Method for Package Yield of Plastic Film
D5047 - Standard Specification for Polyethylene Terephthalate Film and Sheeting
D6287 - Standard Practice for Cutting Film and Sheeting Test Specimens
D6988 - Standard Guide for Determination of Thickness of Plastic Film Test Specimens
D8136 - Standard Test Method for Determining Plastic Film Thickness and Thickness Variability Using a Non-Contact Capacitance Thickness Gauge
E1870 - Standard Test Method for Odor and Taste Transfer from Polymeric Packaging Film
F2029- Standard Practices for Making Heatseals for Determination of Heatsealability of Flexible Webs as Measured by Seal Strength
F2622 - Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using Various Sensors
Books and general references
Hawkins, William E, The Plastic Film and Foil Web Handling Guide CRC Press 2003
Jenkins, W. A., and Osborn, K. R. Plastic Films: Technology and Packaging Applications, CRC Press 1992
Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, ISBN 978-0-470-08704-6