Added "Neural Networks" (#33971)

* Added "Neural Networks"

* fix: removed sentence not needed

guide/english/machine-learning/glossary/index.md

@@ -3,12 +3,10 @@ title: Glossary
 ---
 ## Glossary
 
-A quick one or two sentences describing common terms. See individual pages for
-more details.
-
 - **A/B testing** - A statistical way of comparing two (or more) techniques, typically an incumbent against a new rival. A/B testing aims to determine not only which technique performs better but also to understand whether the difference is statistically significant. A/B testing usually considers only two techniques using one measurement, but it can be applied to any finite number of techniques and measures.
 - **Machine Learning** - Intersection of statistics and computer science in
   order to teach computers to perform tasks without explicitly being programmed.
+  - **Neural Networks** - Learning algorithms based on the brain's neural structure. Neural networks consist of neurons that are connected to each other in different layers. The weight of the connections between the neurons is varied.
   - **Deep Learning** - An umbrella term for machine learning methods based on learning data representations as opposed to algorithms based on fulfilling a given task. It includes architectures such as deep neural networks, deep belief networks and recurrent neural networks.
   - **Neuroevolution** - An umbrella term for machine learning methods based on generating neural networks through weight, bias, and architecture through random mutations of the network. The most common forms of neuroevolution are Neuroevolution of Augmenting Topologies([NEAT](https://en.wikipedia.org/wiki/Neuroevolution_of_augmenting_topologies)) and Interactively Constrained Neuro-Evolution ([ICONE](http://ikw.uni-osnabrueck.de/~neurokybernetik/media/pdf/2012-1.pdf)). 
 - **Statistical Learning** - the use of machine learning with the goal of