Convert URLs into links filter
From Carleton Moodle Docs
As the name suggests, the 'Convert URLs into links and images' filter converts a URL such as http://moodle.org into a clickable link http://moodle.org. In addition it can replace image URLs with images.
Apply to formats
The filter may be applied to text entered in any/all of the following formats: Moodle auto-format, HTML format, plain text format, Markdown format.
Disabling this filter
If you do not want the filter to be applied you can disable at either for a specific activity or for the whole course. To disable for a specific activity, open the activity and then click on the Filters link in the Administration block under Activity Administration. To disable for the entire course page, start from the main course page and then click on Filters in the Administration block under Course Administration.
By default, the filter replaces image URLs with images, however this feature may be disabled by a site administrator.