If you're seeing this message, it means we're having trouble loading external resources on our website.
如果你被网页过滤器挡住,请确保域名*.kastatic.org 和 *.kasandbox.org 没有被阻止.
Updated: June 17th 2021
We may use the information collected through these technologies to better display our website, to save you time, to provide better technical support, for promotional purposes, and to measure and analyze website usage. For example, these technologies help us to:
Purpose and Examples
(also known as Essential or Required Cookies)
Certain cookies and other technologies are essential in order to enable our Service to provide the features you have requested, such as making it possible for you to access our product and information related to your account.
For example, each time you log into our Service, a Strictly Necessary Cookie authenticates that it is you logging in and allows you to use the Service without having to re-enter your password when you visit a new page or new unit during your browsing session.
Strictly Necessary Cookies are necessary to operate our websites, and can’t be switched off. You can set your browser to block (or alert you about) these Strictly Necessary Cookies, but some parts of the Service won’t work as a result.
These cookies provide you with a more tailored experience and allow you to make certain selections on our Service. For example, these cookies store information such as your preferred language and website preferences.
Opting out of Functional Cookies may affect the functionality of the Service. In other words, certain features of the Service depend on cookies – so if you block all cookies, you may not be able to use all aspects of the Service.
You can use your browser settings to opt-out of Functional Cookies. For more information on how to do that, see All About Cookies.
(also known as Performance)
These cookies and other technologies allow us to understand how you interact with our Service (e.g., how often you use our Service, where you are accessing the Service from and the content that you’re interacting with). Analytic cookies enable us to support and improve how our Service operates.
For example, we use Google Analytics cookies to help us measure traffic and usage trends for the Service, and to understand more about the demographics of our users.
We also may use web beacons to gauge the effectiveness of certain communications and the effectiveness of our marketing campaigns via HTML emails.
If you do not allow Analytic Cookies, then we won’t know when you have visited our Service and we won’t be able to monitor its performance.
You may set your email options to prevent the automatic downloading of images that may contain technologies that would allow us to know whether you have accessed our email and interacted with the content. For example, web beacons in emails may be blocked by setting your email preferences to “Plain Text Only”.
These cookies are used on a limited basis, only on pages directed to adults (teachers, donors, or parents). We use these cookies to inform our own digital marketing and help us connect with people who are interested in our Service and our mission.
For general information on managing Tracking Cookie opt-outs, please see Your Choices.
We have provided links to opt-out of these marketing and digital content messages. The Tracking Cookies listed below are examples and subject to change.
(also known as Essential or Required Cookies)
Updates to this Notice
This Cookie Notice may be updated from time to time. If we make any changes, we will notify you by revising the “Effective Date” at the top of this Cookie Notice.
You may be able to refuse or disable cookies by adjusting your web browser settings. Some browsers have options that allow the visitor to control whether the browser will accept cookies, reject cookies, or notify the visitor each time a cookie is sent. Because each web browser is different, please consult the instructions provided by your web browser (typically in the “help” section). If you choose to refuse, disable, or delete these technologies, some of the functionality of the Services may no longer be available to you. And deleting cookies may in some cases cancel the opt-out selection in your browser. Although most browsers and devices accept cookies by default, you can usually manage settings to clear or decline cookies (for instance, by using a “private” or “incognito” mode). If you disable cookies, however, some of the features of our services may not function properly.
To learn more about how to opt-out of ad targeting (and Targeting Cookies), you can go to the Network Advertising Initiative (NAI), the Digital Advertising Alliance’s Consumer Choice (DAA), or Your Online Choices (EDAA) if you are in the European Economic Area. If you use these tools, you will need to opt-out separately for each of your devices and for each web browser on each device. You may also be able to limit interest-based advertising through the settings on your mobile device by selecting “limit ad tracking” (iOS) or “opt-out of interest based ads” (Android).