See why 9,000+ companies trust Darktrace
Thanks, your request has been received
A member of our team will be in touch with you shortly.
Oops! Something went wrong while submitting the form.

What is Content Filtering?

Content filtering definition

Content filtering is the process of screening or restricting objectionable content on the web, in the email inbox, or other mediums. The purpose of content filtering is to prevent access to malicious, inappropriate, or non-compliant content and to enforce organizational policies and regulations.

How does content filtering work?

Content filters work by identifying online communication that needs to be filtered such as website URLs, emails, or SMS. By categorizing the form of communication based on filters set by the user the system can compare the categorized online communication to a list of restricted content. Based on the comparison the system decides to allow or block access the users access to the content. Content filtering can be performed on different levels. Including: 

Network content filtering

At the network level, firewalls can be used to deny access to known websites using IP addresses.

Application content filtering

Using email filters, web filters, or messaging filters you can analyze the content of emails, web pages, or messages, blocking or allowing them based on specific criteria, such as keywords or categories.

Endpoint content filtering

Software can be installed on individual devices to filter content at the endpoint. This can restrict access to certain websites or applications based on specific policies set by an organization.

Types of Content Filters

Web content filtering

Web content filtering is the process of stopping individual users from visiting malicious or inappropriate websites for a variety of reasons including bandwidth usage, compliance regulations and security risks. In cyber security, cyber attackers will use fraudulent emails, like in a phishing attack, to direct users to malicious websites that can compromise a device with malware or steal sensitive information. These websites, once identified, can be blocked by administrators to reduce the risk of a cyber attack. Also, websites such as social media sites can be deemed as "time wasting" sites and web content filters can be used to deny access to these sites.

Block lists

are a type of web content filtering that require users to manually enter the name of each website that they want blocked. This is a common function on home desktops. This can be done in the form of domain based filters in order to filter content based on a sites domain name, disabling your server from recognizing a certain websites IP address. Keyword/content filtering is when an administrator  enters keywords into a database so that the filter can scan a website before it is visited to ensure that it does not contain any of the listed keywords or other content that was defined by the administrator.

Search engine filters

A search engine content filter will instruct the search engine not to show the designated URLs of identified websites. This can be useful for business or individuals seeking to filter content that is inappropriate. When a user is search for information via a search engine, like Google, unwanted or malicious sites can appear on the search engines results. Certain sites can be filtered, stopping potential known watering hole attacks.

Proxy content filter

This is a common method to prevent access to certain websites that might be harmful to users. A proxy content filter acts as a middleman between your server and the internet also allowing administrators to vary user's access to certain websites and information.

Spam email filtering

Spam can come in the form of malicious content masked as advertising (malvertising), or simply be legitimate advertising that overwhelms someone’s inbox. Spam filters is a type of content filter that will automatically send these emails into a spam folder in an effort to eliminate spam content from a user’s inbox.

Email security solutions can provide comprehensive protection and filter content that is both malicious spam and cluttering spam in your inbox.

How Darktrace/Email neutralizes this threat: Darktrace/Email learns the preferred classification of each user's non-productive mail and sorts it into its appropriate place in the inbox. Filtering unwanted content will maximize productivity of employees and reduce the chance of an employee clicking a malicious link that is sent to their business email account.

UI image of non productive mail examples

Why filter content?

Content filtering can be an effective way to prevent cyber attacks, data breaches, and other security incidents like data leakage, as well as to enforce compliance with legal and ethical standards. For example, public institutions are required to have web content filtering. However, it is important to balance the benefits of content filtering with the need to respect individual privacy and freedom of speech.

Prevent malware

Malware is installed on devices when a user clicks on a malicious link or downloads malicious files. With a content filter, administrators can block known websites that contain malicious content. Similarly, in the email inbox, a content filter will automatically send unwanted content into the spam or junk mail folder, reducing the likelihood of a user interacting with malicious content.

Improve employee workflow

To increase productivity content filters can be used to block time wasting sites like social media in order to maintain a productive workforce.

Who should consider content filtering?


Businesses of all sizes can benefit from content filters to protect their networks, devices, and employees from cyber threats, malware, and other harmful content. Content filtering can also help businesses enforce their policies and regulations regarding internet usage and prevent productivity loss due to non-work-related activities. 

Schools and educational institutions

Schools and educational institutions can use content filters to protect their students from inappropriate content and cyberbullying, as well as to prevent access to websites that may distract them from their studies. 

Government agencies

Government agencies can use content filters to protect their networks and data from cyber attacks, prevent the dissemination of sensitive information, and enforce compliance with legal and ethical standards.

Healthcare organizations

Healthcare organizations can use content filters to protect their networks and devices from cyber attacks, prevent data breaches, and enforce compliance with privacy regulations, such as HIPAA.


Individuals who want to protect themselves and their families from malicious or inappropriate content online can use content filtering tools on their devices, such as parental control software, to restrict access to certain websites and applications.

Related glossary terms

This is some text inside of a div block.