Datatypes
The values objects and attributes hold: vectors, colours, sizes and more.
A value object's Value and an attribute can be any of these. Your code reads and combines them with their members and operators; it doesn't construct new ones, since a project's code gets no Vector3.new or other constructors.
Runs today
Vector2A 2D vector: a position or a size on a screen.Vector3A 3D vector: a position, a direction or a size.Color3A colour, each part from 0 to 1.UDimOne axis of a size or position: a scale and an offset.UDim2A size or position on both axes, each a UDim.CFrameA position and a rotation in 3D.NumberRangeA range between a minimum and a maximum.RectA rectangle by its two corners.BrickColorA named colour from a fixed palette, by its number.ShotConnectionThe hold a callback has on an event: keep it, and you can stop listening later.PromiseA value that arrives later: one thread settles it, and any number of others wait for it, each with its own timeout.FlagHolderYour turn with a Flag. Release it and the next thread in line goes.FlagA lock for the threads of one program: whoever asks first gets it first.BinaryWriterWrite numbers, strings, booleans and Vector3s into bytes at exact widths, for a file format or a byte stream.BinaryReaderRead bytes back as numbers, strings and Vector3s, one value at a time, even while more bytes are still arriving.MultipartFormBuild a multipart/form-data body, text fields and files, for an upload or any form post.
Up and coming
TransitionHow a visible change eases: pick a length and a curve, and nothing on screen snaps.IconEvery picture in a window: a file, bytes in memory, a tile of a sprite sheet, an animated strip or a built-in glyph.FontThe typeface for text in a window: the UI font, its semibold, the code font, or a font file of your own.CurveEasing curves as values: build one from bezier points or a function, read its value or speed at any point, and hand it to a Transition.VertexBufferVertex data for a shader draw, uploaded once and used again on every draw.HeightMapA map layer's heights, one byte a pixel, that you can sample at any stud position.