Flashblock is a small extension for Firefox browser, which, as its name suggests, is designed to block Flash animations available on websites. In addition, it also allows you to hide HTML5 and Silverknight videos. During its operation, the tool analyzes the elements of websites that we browse and blocks them when one of the mentioned elements is detected.

In their place, a small icon is displayed, which clicking on it will display the previously hidden component. This extension is an ideal weapon in the fight against unwanted and often irritating components, which can be challenging to close, e.g. when a button to turn off a full-screen advertisement "escapes" from the mouse cursor.

Flashblock also allows the user to create a so-called white list of websites where ads are not blocked by default.