- acknowledgement of humor: tee hee, ha; LOL,
- use of bridging phrases followed by a return (akin to the verbal "um"): but, and
- specific patterns of emoticons and non-standard punctuation
- consistent spelling errors of certain words
- habitual pauses in certain situations, such as breaking a sentence in two for dramatic pause
None of the examples above are exclusive to any specific individual, but in combination they can be unique enough to create a recognizable signature.