There are various ways in which the term 'formats' can be used. We shall review three such ways, noting that all three point towards the same essential feature: recognizability.
This is the most widely used meaning of formats: standardized prescriptive templates defining media genres. Thus, we can speak of the 'talkshow' format, the 'reality TV' the 'breaking news' format, and so forth. Since media programs are intended for mass consumption, they need to be 'formatted' because such formats generate the recognizability of a particular media product as, e.g. a talkshow or reality TV show - instances of a genre we know and to which we can adjust our expectations and criteria for assessment. When we recognize a particular show as a 'talkshow', our expectations are geared towards what we expect of a talkshow (not of, e.g., a horror movie) and we will be able to detect the points where the particular show deviates from or is in accordance with our expectations and criteria for assessment. Formats, thus, orient our media consumption behavior towards specific directions.
A much more specific and technical meaning of 'formats' was developed by sociologist Harold Garfinkel, and refers to the fact that people in social life often engage in jointly established modes of recognizable behavior. The example Garfinkel gave was that of a queue: people congregating at, for instance, a bus stop or the entrance of a theater will almost automatically form an orderly queue, even when no one explicitly calls for that. The queue, thus, is a form of spontaneous social behavior we perform in order to create social order in potentially chaotic situations. But even if the queue is unprompted and spontaneously formed, as soon as the queue is in place, it becomes compelling: people trying to 'jump the queue' will be sanctioned by others. So, even if they remain unspoken, there are rules for forming a queue when social situations call for such forms of order. These rules, of course, are suspended as soon as the queue disappears (when the bus arrives, or when the theater doors are opened).
As in the case of media formats, behavioral formats are also based on recognizability: when we see a queue, we recognize it as such; we will adjust our behavior accordingly and judge the behavior of others along the same parameters.
Media and behavioral formats converge in a lot of what we observe on contemporary social media. Social media users often adopt 'formats' for engaging with others directly as well as indirectly. Indirectly, for instance through the choice of particular profile pictures and self-defining statements (e.g. "lover of jazz and free speech"), and directly, by sticking to well-recognizable genres for organizing social media interaction. But even more important is the way in which online environments serve as learning environments for particular aspects of lifestyle and identity. 'How to' sites and contents are extraordinarily popular online, and in such environents people can find a terrific range of normative indications for becoming and being, for instance, a 'gothic' or 'hipster' girl, for performing certain social roles (e.g. when going out, or going to a posh restaurant), or performing certain acts (from cooking medium-rare steaks and buying the right birthday gift to various forms of trangsgressive behavior). The human body, its appearance and impression on others is perhaps the most widespread object of online formatting.
Formats online are algorithmically important: it is through the recognizaibility of online behavior that such behavior can be converted into 'data' for algorithmic processing.
Online formatting does spill over into offline formats, as when mass online mobilization around incidents such as terror attacks or other disasters leads to large-scale offline demonstrations in which people show, wear or apply identical symbols (think of what happened after the Paris attacks on Charlie Hebdo, and the popularity of the hashtag '#JeSuisCharlie' in offline commemoration events worldwide).