 Published on
Markdown
To understand markdown we first need to understand HTML. HTML stands for HyperText Markup Lanaguage. It requires extremely strict syntax so that browsers can draw the document correctly.
Markdown is almost the opposite, but not quite. Markdown is a way of producing HTML with simple syntax.
 Simple, forgiving syntax generates the HTML for you.
 No special editor required.
 Easier than writing HTML.
 Powerful! It can be extended to do more than HTML.
 Has its limitations! It is not intended to replace HTML but rather to make it easier to generate HTML.
Common HTML Tags
We can use markup to create HTML.
Tag  Name  Syntax/Example  Comments 

p  Paragraph  Simply type text with a space above and below it  
h1  Heading 1  # X  Heading1 X 
h2  Heading 2  ## X  Heading2 X will be drawn 
h3  Heading 3  ## X  Heading3 X will be drawn 
h4  Heading 4  ## X  Heading4 X will be drawn 
h5  Heading 5  ## X  Heading5 X will be drawn 
h6  Heading 6  ## X  Heading6 X will be drawn 
blockquote  Blockquote  >  Display X as a quote 
ul  List   X  Unordered list item X 
ol  Ordered List  ol  Ordered item 1. X 
table  Table  Pipes are used for columns. Dashes for second row.  
code  Code  code 

inlineCode  InlineCode  inlineCode 

em  Emphasis  _emphasis_ 

strong  Strong  **strong** 

del  Strikethrough  ~~strkethrough~~ 

hr  Thematic break   or \*\*\* 

a  Link  <https://xyz.com> OR [link text to show](<)https://xyz.com) 

img  Image  ![alt(https://source.jpg)] 
Level Up!
Now the creators of markup are fairly smart people. They realized that the idea of generating HTML with basic syntax was a good idea. So they took it a step further and allowed the syntax to create complex HTML, styling and functionality!
Inline Highlighting
Sample of inline highlighting sum = parseInt(num1) + parseInt(num2)
is done by wrapping text in tick(`) marks.
Blocks Highlighting
Block wrapping of text is done by wrapping it with three tick (```) marks before and after.
This is a paragraph.
This is some more stuff.
Math Formulas
Math formulas are very difficult to draw, even in HTML. With markdown
and KATEX they are an order of magnitude easier.
$$\mathbf{Y} = \left[\begin{array} {c} p_1 \\ . \\ . \\ . \\ p_n\end{array}\right]$$
produces
$$c = \pm\sqrt{a^2 + b^2}$$
produces
Least Squares
Start:
y_i = \mathbf{x}'_i \beta + u_i
Assumptions:
 Linearity (given above)
 E(\mathbf{U}\mathbf{X}) = 0 (conditional independence)
 rank(\mathbf{X}) = k (no multicollinearity i.e. full rank)
 Var(\mathbf{U}\mathbf{X}) = \sigma^2 I_n (Homoskedascity)
Aim:
Find \beta that minimises sum of squared errors:
Solution:
Hints: Q is a 1 \times 1 scalar, by symmetry \frac{\partial b'Ab}{\partial b} = 2Ab.
Take matrix derivative w.r.t \beta:
\begin{aligned} \min Q & = \min_{\beta} \mathbf{Y}'\mathbf{Y}  2\beta'\mathbf{X}'\mathbf{Y} + \beta'\mathbf{X}'\mathbf{X}\beta \\ & = \min_{\beta}  2\beta'\mathbf{X}'\mathbf{Y} + \beta'\mathbf{X}'\mathbf{X}\beta \\ \text{[FOC]}~~~0 & =  2\mathbf{X}'\mathbf{Y} + 2\mathbf{X}'\mathbf{X}\hat{\beta} \\ \hat{\beta} & = (\mathbf{X}'\mathbf{X})^{1}\mathbf{X}'\mathbf{Y} \\ & = (\sum^{n} \mathbf{x}_i \mathbf{x}'_i)^{1} \sum^{n} \mathbf{x}_i y_i\end{aligned}
Markup can produce Footnotes!
Generate footnote #1 by starting it with a [^1]
. It will automatically appear at the foot of the page, not where you place it.
[^1]: Draw this at the bottom as footer notation 1.
[^2]: This footer will automatically be shifted to the bottom of the page.
Should my website support markdown?
Being able to add blogs and pages using a simple editor is handy. It is much faster to produce documents and generates cleaner, faster web pages as a result. This speeds up your Google Insight's rating and helps dramatically with SEO.
Nerdspeak
Now let's talk a little nerd. If you don't follow, that's okay. This is for us nerds.
MDX blends markdown and JSX syntax. You can import JSX components and render them in your MDX document. Markdown is created at compile time so it is super fast!
Markup Blogs
This blog uses markdown technology to generate HTML easily. I'm not using a fancy editor to build these blogs. I'm just typing and the markdown does the hard work.