A signature - remember that? The thing you do with a pen to pretend you were you, in the days before contactless debit cards, Android pay and the digital age...
(Soon to be rendered obsolete by standardised fingerprint checks).
People's handwriting has long been studied for clues about the personality or psychological make up of the writer - although this practice has also been widely debunked.
But various studies argue that signatures, rather than handwriting, can genuinely serve as indicators of character because the signature is inherently more personal.
Many also show that size of signature can be the true giveaway.
Let's take a closer look at what your signature can tell us about you...
1. Financial success
This 2014 paper examined the signatures, salaries and company success of various CEOs.
It found that bigger signatures were associated with higher salaries.
However, they were also indicators of poorer company performance.
2. Social dominance
This study published in the Journal of Research in Personality examined the relationship between three different signature sizes and various personality traits, keeping number of letters, average writing size and signature style as controlled variables.
According to the results, a large signature indicated "sociable dominance" in both males and females.
The same study indicated that the size of signature signified narcissism - but only in females.
That echoes the findings of this 1987 study, which measured embellishments on signatures (such as underlinings or exclamation points).
While embellishments didn't appear to indicate anything among the male students, among the females they were associated with significantly higher levels of narcissism.
People who urge you to read a document before you sign it may want to consider this study.
According to the research, signing a document at the beginning of a document (e.g. tax return or insurance policy forms) rather than at the end, significantly reduces dishonesty.
5. Self esteem
This study suggested that signature size could also be linked to self esteem.
According to the research, giving people inflated feedback on an IQ test, which improved their confidence, resulted in them using a larger signature.