how to calculate NDVI using LANDSAT 8 in google earth engine

In this tutorial, I will present how to calculate NDVI using Landsat 8 images in Google Earth Engine
Google Earth Engine (EE) is a cloud/browser-based platform for planetary scale geospatial analysis that relies on Google's processing and storage capabilities to enable large analyses in very little time. Earth Engine is home to hundreds of public remote sensing/geospatial datasets totaling more than thirty petabytes, and is continuously updated as images are captured. Here, we take advantage of the up-to-date and easy-to-access satellite imagery in Earth Engine to calculate and display a vegetation index (NDVI) from recent Sentinel imagery, anywhere on earth.
Besides tabular and time-series data, Data Scientists or Data Analysts can also draw information and insight from image data and demonstrate satellite image analysis using Google Earth Engine, or referred to as Earth Engine. Satellite images are raster data just like any image. What makes them different is that satellite images have spatial attributes. Each pixel represents a location in the real world. Analyzing satellite images means we are going to get information on what is in our study area. The science focusing on studying this field is Remote Sensing.
Earth Engine is a platform to perform Remote Sensing, like satellite image analysis. It has many satellite images in its archive. I am not going to explain much about Earth Engine and Remote Sensing here because I have done it in another article here. If you are not familiar with Remote Sensing or Earth Engine, please find yourself a simple explanation in that article. That article actually performed how to apply Machine Learning for land cover detection on Landsat 8 images.
Normalized Difference Vegetation Index (NDVI) using Landsat 8 images too. NDVI is an index commonly used in satellite image analysis to get basic information on vegetation distribution.
Landsat 8 images, just like other images, consist of pixels. Each pixel contains values. While the colorful image has 3 bands, usually red, green, and blue, Landsat 8 has 11 bands. Two of these bands used to generate NDVI are band 5 (NIR) and band 4 (Red). Figure 1 is the spectral curves showing spectral response to 3 objects. The green curve represents the spectral response to vegetation. We can see that vegetation reflects NIR the most and absorbs the red spectrum the most. Other objects have different characteristics. The water barely reflects the red spectrum and reflects all NIR. Soil reflects less NIR but reflects more red spectrum than vegetation does.

[@alexisahohoundo83]

Please how to extract monthly datas of NDVI or another parameters in CSV format with GEE?

[@LORENAIVONNESALDAÑAREYES]

Thanks, very usefull! Just a doubt, I'm a beginner in using GEE, why the scale of image is 30?

[@amaregebrie6834]

It is the resolution of the Landsat 8 Image

[@wahyuhaikal6022]

why do i get this message while running
"ndvi image: Layer error: Image.select: Band pattern 'B4' was applied to an Image with no bands."

[@azcomap]

facing the same issue

[@tanyto15]

You cant substract from an ee.ImageCollection . the console will type "nir.subtract is not a function"

[@gisrsprofessionals6246]

You have missed something

[@gisrsprofessionals6246]

You have missed something

[@YasminRashid-oh4tu]

How do you correct this

[@maileletsoalo7443]

I am facing the same issue

[@YasminRashid-oh4tu]

@@maileletsoalo7443 After image write .first()

[@UmairAhmad-j8i]

thank you

[@PaoloBiso-wq5my]

I can't view the image in desktop Qgis, why is it??

[@gisrsprofessionals6246]

You have to change image properties in software

[@MelM00l]

this code doesn't work!!!

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Boyle Prairie

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Jalyn Forest

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Green Corner

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Kuhic Ridge

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Lebsack Plains

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Asha Rue

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Elfrieda Burg

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Everardo Causeway

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Keshaun Ports

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Krajcik Meadows

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Hermiston Courts

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Vivienne Turnpike

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Hane Gateway

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Celia Way

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Gottlieb Rue

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Juanita View

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White Rest

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Cedrick Flats

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Adrien Street

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Donny Crossing

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Jones Estate

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Imani Harbors

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Wisoky Harbors

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Hessel Oval

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Jaylan Lights

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Hamill Passage

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Hintz Estate

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Conroy Ville

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Pietro Squares

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Tristin Parkways

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Franecki Fields

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Reagan Isle

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DuBuque Light

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Jalon Court

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Frami Burg

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Dangelo Square

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Jedediah Street

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Lind Route

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Anastacio Ports

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Bechtelar Locks

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Beier Isle

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Kling Keys

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Collier Spurs

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Meredith Land

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Wiegand Causeway

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Von Villages

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Leffler Way

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Keara Pike

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Ziemann Unions

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Pfannerstill Ford