Private messaging is one of the main ways that people interact on Facebook. This type of direct messaging can be either an instant message (chat), or a regular email-type message. For both instant and regular messaging, there is a 20,000 character limit.
A Facebook status may have character limits, but considering that it is at 63,206 characters, unless you are writing War and Peace, you should be fine. Facebook has raised this number 12 times to accommodate user’s status and feedback.
Facebook wall posts have a 5000 character limit, but truncation begins at 477 characters. This enables someone to write a thoughtful response or create something similar to a blog.
An area which is rarely used in Facebook is the Notes section. It is a writing area which many bloggers find useful. The reason is because Facebook Notes does not have a character limit, as of yet. Users are directed to this area if they have very long status or comment to make. This can be used to someone's advantage if they have a longer post to make and wish to share it with their friends through tagging.
At Facebook, users upload and post new photos every day. When uploading pictures, users may need to write a description, which has a 5000 character limit. Once uploaded, few friends will comment about the post, which should give them a character limit of 8000 characters.
On news feeds, long posts only show the first 1,200 or so characters.
To summarize Facebook character limits: