A script with that visitors can add comments on webpages. It can be included in php files and html files. The comments are saved in a text file, so no database is required. Contains an admin script to edit and delete the comments.
Most scripts are free or open source. But some have the full source code available for download yet itīs required to have permission to use them and most often the price will be listed. If there is a script license e.g. GNU or GPL then it will also be listed.