Machine Learning 101: What It Is, How It’s Used, and the 3 Types of Machine Learning 

Written by Coursera • Updated on

Machine learning is an exciting field and a subset of artificial intelligence. Use this guide to discover more about real-world applications, and the three types of machine learning, which include supervised, unsupervised, and reinforcement learning.

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Machine learning is a specialized technology that falls under the umbrella of artificial intelligence (AI). This exciting field is the driving power behind many modern technologies, including image recognition and self-driving cars. It makes it possible for machines to develop problem-solving models using various specific algorithms among the types of machine learning. Those algorithms help machines identify patterns in data.

The global machine learning market is predicted to grow to more than $152 billion by 2028, up from $15.5 billion in 2021, according to Fortune Business Insights [1]. It’s a complex, but exciting field responsible for innovations like Amazon Alexa's ability to choose your most played music station when you ask her to queue your favorite station. 

Machine learning is the driving force behind social platforms like Facebook's ability to suggest articles in your feed based on your interactions. Machine learning holds the promise of transforming many of our everyday experiences. It's also an in-demand career field that's well-suited to those interested in data science and AI.

What is machine learning?

This branch of AI focuses on using data and algorithms to mimic human learning, allowing machines to improve over time, becoming increasingly accurate when making predictions or classifications, or uncovering data-driven insights. It works in three basic ways, starting with using a combination of data and algorithms to predict patterns and classify data sets, an error function that helps evaluate the accuracy, and then an optimization process to fit the data points into the model best.

Did you know?

Arthur Samuel created the term "machine learning" in reference to his research in the early 1960s. That research was based on the checkers game that Robert Nealy played against an IBM 7094 computer and lost. Although this is minor compared to what machines can do today, it was a groundbreaking milestone at the time.

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Applications of machine learning 

Machine learning is already used around us and you may not realize how it impacts your life. One example is the spam filter of your email provider. That filter uses an algorithm to continually identify new types of junk messages. and moves them to your spam folder instead of into your inbox. And that's not the only real-world application of machine learning that you’re already using. 

Social media features

Social media platforms integrate machine learning algorithms to help deliver personalized experiences to you. Facebook notes your activities, including your comments, likes, and the time you spend on different types of content. The algorithm learns from your activity and makes pages and friend suggestions tailored to you.

Virtual assistants

Apple's Siri, Amazon's Alexa, and Google Now are all popular options if you're looking for a virtual personal assistant. These voice-activated devices can do everything from search for flights to check your schedule to set alarms and more. Machine learning is a key component of these smart devices and speakers. They collect information and refine it each time you interact with them. The machine can then use that data to give you results that are best matched to your preferences.

Product recommendations 

Popular among e-commerce websites, product recommendations are a common machine learning application. It lets these sites track your behavior based on your searches, previous purchases, and your shopping cart history to make suggestions and recommendations about products you may be interested in.

Image recognition 

Image recognition is a complex technology that holds promise in a variety of fields. In your everyday life, you've probably come across this while uploading a photo to your social media platform. When you tag someone in an image, the platform recognizes them. It can also be transformative for identifying potential threats or criminals, unlocking phones and mobile devices, and finding missing persons.

3 types of machine learning  

Machine learning involves showing a large volume of data to a machine so that it can learn and make predictions, find patterns, or classify data. The algorithm used determines the machine learning type, which works a bit differently. There are three machine learning types: supervised, unsupervised, and reinforcement learning.

Supervised learning

Gartner, a business consulting firm, predicts that supervised learning will remain the most utilized machine learning among enterprise information technology leaders in 2022 [2]. This type of machine learning feeds historical input and output data in machine learning algorithms, with processing in between each input/output pair that allows the algorithm to shift the model to create outputs as closely aligned with the desired result as possible. Common algorithms used during supervised learning include neural networks, decision trees, linear regression, and support vector machines.

This machine learning type got its name because the machine is “supervised” while it's learning, which means that you’re feeding the algorithm information to help it learn. The outcome you provide the machine is labeled data, and the rest of the information you give is used as input features. 

For example, if you were trying to learn about the relationships between loan defaults and borrower information, you might provide the machine with 500 cases of customers who defaulted on their loans and another 500 who didn't. The labeled data “supervises” the machine to figure out the information you're looking for.

Supervised learning is effective for a variety of business purposes, including sales forecasting, inventory optimization, and fraud detection. Some examples of use cases include:

  • Predicting real estate prices

  • Classifying whether bank transactions are fraudulent or not

  • Finding disease risk factors

  • Determining whether loan applicants are low-risk or high-risk

  • Predicting the failure of industrial equipment's mechanical parts

Unsupervised learning

While supervised learning requires users to help the machine learn, unsupervised learning doesn't use the same labeled training sets and data. Instead, the machine looks for less obvious patterns in the data. This machine learning type is very helpful when you need to identify patterns and use data to make decisions. Common algorithms used in unsupervised learning include Hidden Markov models, k-means, hierarchical clustering, and Gaussian mixture models.

Using the example from supervised learning, let's say you didn't know which customers did or didn't default on loans. Instead, you'd provide the machine with borrower information and it would look for patterns between borrowers before grouping them into several clusters.

This type of machine learning is widely used to create predictive models. Common applications also include clustering, which creates a model that groups objects together based on specific properties, and association, which identifies the rules existing between the clusters. A few example use cases include:

  • Creating customer groups based on purchase behavior

  • Grouping inventory according to sales and/or manufacturing metrics

  • Pinpointing associations in customer data (for example, customers who buy a specific style of handbag might be interested in a specific style of shoe)

Reinforcement learning

Reinforcement learning is the closest machine learning type to how humans learn. The algorithm or agent used learns by interacting with its environment and getting a positive or negative reward. Common algorithms include temporal difference, deep adversarial networks, and Q-learning.

Going back to the bank loan customer example, you might use a reinforcement learning algorithm to look at customer information. If the algorithm classifies them as high-risk and they default, the algorithm gets a positive reward. If they don't default, the algorithm gets a negative reward. In the end, both instances help the machine learn by understanding both the problem and environment better.

Gartner notes that most ML platforms don't have reinforcement learning capabilities because it requires higher computing power than most organizations have [2]. Reinforcement learning is applicable in areas capable of being fully simulated that are either stationary or have large volumes of relevant data. Because this type of machine learning requires less management than supervised learning, it’s viewed as easier to work with dealing with unlabeled data sets. Practical applications for this type of machine learning are still emerging. Some examples of uses include:

  • Teaching cars to park themselves and drive autonomously

  • Dynamically controlling traffic lights to reduce traffic jams

  • Training robots to learn policies using raw video images as input that they can use to replicate the actions they see

5 career paths in machine learning 

The World Economic Forum's “Future of Jobs Report 2020” predicts that machine learning and all of artificial intelligence will generate 97 million new jobs around the world by 2025 [3]. In 2019, Indeed ranked machine learning engineer number one on its list of the Best Jobs in the United States, noting its 344 percent growth rate [4]. Machine learning is an in-demand field that lends itself to several possible career paths, including:

*All salary data sourced from Glassdoor as of March 2022

1. Machine learning engineer

In this role, you can work on machine learning projects and create and manage platforms. 

Average annual salary (US): $131,001 

2. Data scientist

In this role, you can use a combination of machine learning and predictive analytics to collect, analyze, and interpret data. 

Average annual salary (US): $117,212 

3. Natural language processing (NLP) scientist

In this role, you can work with computers, computer science, and computational language to form connections between the way humans communicate and computers understand and interpret human language. 

Average annual salary (US): $94,101 

4. Business intelligence developer

In this role, you’ll focus on analyzing data to gather insight into business and market trends. 

Average annual salary (US): $94,743 

5. Human-centered machine learning designer

In this role, you can design, develop, and deploy systems that learn from humans. 

Average annual salary (US): $94,468 

How to get started in machine learning

Most employers look for a combination of education and experience. Here are three common ways to set yourself on the path to the job you want: 

  1. Get a start in your career path by earning a bachelor's degree in data science, computer, programming, computer science, or a related field. 

  2. Gain work experience in roles such as software development, software programming, computer engineering, or data science.

  3. Consider earning a master's degree. Most employers prefer machine learning professionals with an advanced degree in software engineering, computer science, machine learning, or AI.

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Next steps

Learn the fundamentals of machine learning with Stanford’s popular Machine Learning course, or develop the skills needed to build and train deep neural networks with the Deep Learning Specialization from DeepLearning.AI. If you’re serious about a career in machine learning, explore how a data science degree could unlock new opportunities.

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Article sources

1. Fortune Business Insights. “Hardware and Software IT Services, https://www.fortunebusinessinsights.com/machine-learning-market-102226.” Accessed March 11, 2022.

2. Gartner. “Understand 3 Key Types of Machine Learning, https://www.gartner.com/smarterwithgartner/understand-3-key-types-of-machine-learning.” Accessed March 11, 2022.

3. World Economic Forum. “Don’t fear AI. It will lead to long-term job growth, https://www.weforum.org/agenda/2020/10/dont-fear-ai-it-will-lead-to-long-term-job-growth/.” Accessed March 11, 2022.

4. Indeed. “The Best Jobs in the US in 2019, https://www.indeed.com/lead/best-jobs-2019.” Accessed March 11, 2022.

Written by Coursera • Updated on

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