There are several basic shapes used for most SVG drawing. The purpose of these shapes is fairly obvious from their names. Some of the parameters that determine their position and size are given, but an element reference would probably contain more accurate and complete descriptions along with other properties that won't be covered in here. However, since they're used in most SVG documents, it's necessary to give them some sort of introduction.

The <foreignObject> SVG element includes elements from a different XML namespace. In the context of a browser, it is most likely (X)HTML.

The glyphRef element provides a single possible glyph to the referencing <altGlyph> substitution.

The addition (+) operator produces the sum of numeric operands or string concatenation.

The svg element is a container that defines a new coordinate system and viewport. It is used as the outermost element of SVG documents, but it can also be used to embed an SVG fragment inside an SVG or HTML document.

The arabic-form attribute indicates which of the four possible forms an Arabic glyph represents.

The isNaN() function determines whether a value is NaN, first converting the value to a number if necessary. Because coercion inside the isNaN() function can be surprising, you may prefer to use Number.isNaN().

The <feColorMatrix> SVG filter element changes colors based on a transformation matrix. Every pixel's color value [R,G,B,A] is matrix multiplied by a 5 by 5 color matrix to create new color [R',G',B',A'].

The <feComponentTransfer> SVG filter primitive performs color-component-wise remapping of data for each pixel. It allows operations like brightness adjustment, contrast adjustment, color balance or thresholding.

The decodeURI() function decodes a Uniform Resource Identifier (URI) previously created by encodeURI() or a similar routine.