Stickers

[Christoph Päper]

William_J_G Overington via Unicode <unicode at unicode.org>:
> 
> What exactly is a sticker please?

A sticker in this context is only used within instant messaging (IM) platforms and apps. It is an vector drawing (mostlySVG) or raster image (PNG or WebP or, rarely, JPEG) that is often part of a larger set of visually or thematically related graphics. Those might be, but usually are not, packaged inside a font format file. Each sticker exemplifies an emotion, reaction or concept, which may be associated with one or more Unicode emojis as a kind of tag or keyword to facilitate simple search or suggestions for substitution. 

Stickers are considered more personalized than standardized emoji, because, at least in principle, each user could design and share their own. Apple Memoji and similar solutions by other vendors can be considered personalized dynamic sticker (and avatar) generators, in this case  sharing graphic base models with the emoji font used by that vendor. 

Gifs are short animated image sequences or video clips without audio track that historically used Compuserve’s 8-bit graphics interchange file format (GIF89a), but nowadays APNG, WebM/MKV+VPx or MP4/H.26x. A gif is usually not part of a set, but it is often shared through public services. They are used to visualize emotions or to emphasize reactions and sometimes purely for decoration. 

Memes may be gifs, but are more often still images (mostly comics, photographs or captured video frames, often in JPEG format), frequently including textual overlays. They reference short-lived phenomena from popular culture to exemplify reactions. Based on a single consistent visual component, memes usually have countless variations, but otherwise are not part of a set. 

What makes all of these related to emojis is that they visually augment or even replace written performative acts in a primarily text-based communication medium, often in 1:1 or m:n scenarios like chat and social media and less often in 1:n prose.