You may wish to begin by reading the <link linkend="TextWidget">text widget conceptual overview</link> which gives an overview of all the objects and data types related to the text widget and how they work together. Ais like a bookmark in a text buffer; it preserves a position in the text. You can convert the mark to an iterator using gtk_text_buffer_get_iter_at_mark(). Unlike iterators, marks remain valid across buffer mutations, because their behavior is defined when text is inserted or deleted. When text containing a mark is deleted, the mark remains in the position originally occupied by the deleted text. When text is inserted at a mark, a mark with <firstterm>left gravity</firstterm> will be moved to the beginning of the newly-inserted text, and a mark with <firstterm>right gravity</firstterm> will be moved to the end. <footnote> "left" and "right" here refer to logical direction (left is the toward the start of the buffer); in some languages such as Hebrew the logically-leftmost text is not actually on the left when displayed. </footnote> Marks are reference counted, but the reference count only controls the validity of the memory; marks can be deleted from the buffer at any time with gtk_text_buffer_delete_mark(). Once deleted from the buffer, a mark is essentially useless. Marks optionally have names; these can be convenient to avoid passing the object around. Marks are typically created using the gtk_text_buffer_create_mark() function.