email html. First encountered! Code for inserting segmented content into the newsletter?

Question

HTML

I was given this code, what should I do with it? And what does this have to do with writing letters?

To insert segmented content into the mailing list

%%[IF (([Speciality] == "Neurology")) THEN]%%
%%=BeginImpressionRegion("01__Rule_1")=%%
NEURO
%%=EndImpressionRegion()=%%
%% [ELSE]%%
Not
%%[ENDIF]%%

Answer 1

It looks like specific comments for embedding into some kind of mailing service. Example from mailchimp - link At least it looks like it.