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What Is Bot and How Does It Work?

Vejune Tamuliunaite

Vejune Tamuliunaite

2021-07-135 min read

A bot is a software program that is mainly used to automate certain tasks so they could be run without further human instructions. One of the main reasons for using bots is their ability to perform automated tasks much faster than humans.

In this article, we will explain how bots work, their main types, and how good and malicious bots differ from each other.

How do bots work? 

Bots are designed from sets of algorithms that help them in their appointed tasks. From conversing with a human to gathering content from a website – there are numerous types of bots differently made to achieve a wide range of tasks. 

For instance, there are numerous methods of operation by which a chatbot can run. While a rule-based bot will interact with humans by providing predefined options to select from, an intellectually sophisticated bot will use machine learning to learn and look for specific keywords. Such bots may also employ tools for pattern recognition or natural language processing (NLP). 

For obvious reasons, bots do not click on content in a traditional browser and do not operate a mouse. They typically do not access the internet via web browsers as human users do. Instead, bots are software programs that send HTTP requests besides other tasks and usually use a headless browser.

Types of bots

There are many types of bots active on the internet utilizing all sorts of tasks. Some of them are legitimate, while some operate for malicious purposes. Let’s go through the main ones to get a better understanding of how the bots ecosystem works.

Web crawlers 

Web crawlers, also known as web spiders or spider bots, scan content over the internet. These bots help search engines to crawl, catalog, and index web pages in order to provide their services efficiently. Crawlers download HTML, CSS, JavaScript, and images and use them to process the content of the site. Website owners might place a robot.txt file in the root of a server, thus informing bots which pages they can crawl.

Monitoring bots

Site monitoring bots monitor the health of the system, such as loading times. This allows website owners to identify possible issues and improve user experience. 

Scraper bots

Web scraping bots are similar to crawlers, but they are used for reading publicly available data from websites with the objective of extracting specific data points, for example scrape real estate data, and etc. Such data could be used for research purposes, ad verification, brand protection, etc.


As mentioned previously, these bots can simulate human conversations and respond to users with programmed phrases. One of the most famous chatbots was created in 1963, prior to the web, and called Eliza. It pretended to be a psychotherapist and mostly turned users’ statements into questions based on specific keywords. Nowadays, most chatbots use a combination of defined scripts and Machine Learning.

Spam bots

Spam bots are malicious bots that scrape email addresses for the sole purpose of sending unsolicited and unwanted spam emails with nefarious intents. Spammers may also perform even more hostile attacks, such as cracking credentials or phishing.

Download bots

Download bots are used to automate multiple downloads of software applications in order to increase statistics and gain popularity in app stores. 

DoS or DDoS bots

DoS or DDoS bots are designed to take down websites. An overwhelming amount of bots attack and overload a server stopping the service from operating or weakening its security layers. 

What is malicious bot activity?

It is easy to tell the difference between malicious and good bots when we know the ultimate intent. So the goal is to define whether bots’ activity is harmful or not. Another example, some bots are designed to utilize neutral tasks, like colorizing black and white photos on Reddit, while malware bots may be used to gain absolute control over a computer.

For better understanding, this is the most common malicious bot activity:

  • Spam content

  • DoS (Denial of Service) or DDoS (Distributed Denial of Service) attacks

  • Credentials stuffing

  • Click fraud

According to research, malicious bots activity grew to its highest ever percentage of 24.1% of all online traffic in 2019. This means that 37.2% of overall traffic was not human. 

How do websites detect bots?

Websites have developed numerous methods and techniques to detect bot traffic and block it. From simple daily encountered CAPTCHAs to complex measures, they all help to reduce the exposure to bots:

  • Following the parameters on web analytics can indicate bot traffic on a website:
    A slowdown in loading times
    Odd traffic patterns, especially when it happens not during common peak hours. 
    Suspicious IPs or activity from unusual geo-locations.
    Many requests from a single IP (unlike humans, bots often request all web pages)

  • Placing CAPTCHAs on a website’s sign-up or download forms. This challenge-response type of test helps to prevent spam bots. Tip: check this blog post on how do CAPTCHAs work.

  • Adding a robot.txt file in the root of the website servers serves as entry rules for bots which pages can be crawled and how frequently.

  • Checking browser fingerprinting allows indicating the presence of attributes added by headless browsers.

  • Setting a detection tool as an alert to notify of a bot entering a website. 

  • Inspecting behavioral inconsistencies, such as repetitive patterns, nonlinear mouse movements, or rapid clicks, can also be a sign of a bot-like behavior.

These and many other anti-bot measures allow websites to spot bots and ultimately block them. If you are interested in how websites recognize suspicious behavior, read our blog article How Websites Block Bots.

Anti-bot methods and web scraping

Over decades bot technologies have evolved and become more sophisticated, accepting cookies and parsing JavaScript. Most advanced bots can imitate human activity and are hard to distinguish from real users. As a result, website owners strive to add extra layers of anti-bot protection to their servers and look for new solutions. 

This affects web scraping and brings more challenges for scrapers to gather publicly available information for fair purposes without getting flagged and blocked. Some websites provide basic guidelines of web scraping, while others might be aiming to stop it altogether. 

Web scraping without getting blocked

With anti-bot measures improving, Oxylabs offers several solutions for successful ethical web scraping.

Web Unblocker

Web Unblocker is an AI-powered proxy solution for effortless web data gathering. Web Unblocker has exceptional performance and successfully bypasses CAPTCHAs and IP bans. This advanced web scraping solution lets you scrape even the most challenging publicly available data without blocks. 

Main Web Unblocker features:

  • Dynamic browser fingerprinting

  • ML-driven proxy management

  • ML-powered response recognition

  • Auto-retry functionality

  • JavaScript rendering

Web Scraper API

Web Scraper API is an all-in-one solution for efficient web scraping. Our data scraper API can help you gather real-time data from any public website. It is easy to use and does not require any additional resources or infrastructure from a client’s side. Web Scraper API helps reduce costs since users pay only for successfully delivered results. 

More features:

  • Provides structured data from leading e-commerce websites and search engines

  • Includes Proxy Rotator for block management

  • Highly customizable and supports high volumes of requests

  • Requires zero maintenance: handles website changes, IP blocks, and proxy management


As bot technologies develop continuously, website owners implement advanced anti-bot measures to their sites. This brings an additional challenge to web scrapers that gather public data for science, market research, ad verification, etc. and get blocked. Luckily, Oxylabs offer several solutions for efficient and block-free web scraping with high success rates. 

Since now you know how websites detect and block bots, check out our blog and read more about crawling a website without getting blocked. Also, before engaging in any web scraping activity, find out more about the complex question Is Web Scraping Legal?.

About the author

Vejune Tamuliunaite

Vejune Tamuliunaite

Former Product Content Manager

Vejune Tamuliunaite is a former Product Content Manager at Oxylabs with a passion for testing her limits. After years of working as a scriptwriter, she turned to the tech side and is fascinated by being at the core of creating the future. When not writing in-depth articles, Vejune enjoys spending time in nature and watching classic sci-fi movies. Also, she probably could tell the Star Wars script by heart.

All information on Oxylabs Blog is provided on an "as is" basis and for informational purposes only. We make no representation and disclaim all liability with respect to your use of any information contained on Oxylabs Blog or any third-party websites that may be linked therein. Before engaging in scraping activities of any kind you should consult your legal advisors and carefully read the particular website's terms of service or receive a scraping license.

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I’m interested


  • How do bots work? 

  • Types of bots

  • What is malicious bot activity?

  • How do websites detect bots?

  • Anti-bot methods and web scraping

  • Web scraping without getting blocked

  • Conclusion

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