font-FiraCode/googlefonts-qa/gfonts-description.html

<p>Programmers use a lot of symbols, often encoded with several characters. For the human brain, sequences like
    <code>-&gt;</code>, <code>&lt;=</code> or <code>:=</code> are single logical tokens, even if they take two or three
    characters on the screen. Your eye spends a non-zero amount of energy to scan, parse and join multiple characters
    into a single logical one. Ideally, all programming languages should be designed with full-fledged Unicode symbols
    for operators, but that’s not the case yet.
</p>
<p>
    Fira Code is an extension of the Fira Mono font containing a set of ligatures for common programming multi-character
    combinations. This is just a font rendering feature: underlying code remains ASCII-compatible. This helps to read
    and understand code faster. For some frequent sequences like <code>..</code> or <code>//</code>, ligatures allow us
    to correct spacing.
</p>