Signatures - How are they done?

I've seen a wide variety of signatures in my time here (mostly on blogs and/or comments). This is both a question and descripion.

Some are non-existant and/or very simple:

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Thanks,
Annette

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Others are more elaborate, and include a quote:

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Annette
"Never ascribe to malice that which can be explained by incompetence." - Napoleon

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or some such variation in font/postioning. Yet others appear to include thumbnail photos/images:

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Annette MacGregor

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And, of course, there are those that combine things.

My question is more (since many are always the same) how does one achieve the sameness? Store the "code" for the signature and paste it in? Or, key it in each time? Or, is there a way to register a signature and say when it is supposed to be added by BCTS?

Thanks - to any that respond.