Which typeface (font?) to use and why

The 10 Most Popular Web Fonts of 2015

Ref: Choosing the right font

Contrast Ratio: Formula W3C

Email constraints:
Mailchimp says
from Bloomberg
Jan Constantin – Smashing mag
** StyleCampaign

Type+Place: Type Inspired by India
from Wanderlust Designer: On Typography

from keycdn.com Case Study – Analyzing Web Font Performance

Core web fonts

10 Web Design Tools to Discover Beautiful Fonts for Your Next Project

21 Stunning Serif Fonts for the Modern Website

One Kings Lane
Oribe – for headings