Skim was originally designed for reading and annotating scientific papers in PDF, but it has also become a PDF reader and note-taker for Mac OS X. It features a table of contents which displays the chapters that have already been read, they are marked differently from unread chapters. The table of contents pane may also be used for conducting a quick search on a specific word or phrase from the document, users may set a preference to search by words or relevance, which will help in books with thousands of pages. The software can create notes within the PDF document. Notes can be added directly on the page to remind the user about something useful in the book or regarding the text that was read. Another type of note is the Anchored Note, which is used for longer notes. A title and icon may be assigned to it and it becomes a small icon that will pop-up when double clicked. Documents may also be annotated and drawing of circles, rectangles, and lines and also highlighting text are allowed by the software. Snapshots of important sections of a PDF document may be taken for reference, so users won't have to leaf back to each section just to view it. These annotations and snapshots are acessible through the Notes Pane, which can be shown or hidden. When notes need to be deleted, users will just have to right click on the item contained in this pane and choose Delete. Other editing commands may also be used like Copy, Edit and Select.