Glossary
Index fund
A fund that mechanically holds every company in a market index.
Rather than paying someone to pick winners, an index fund buys the whole market at very low cost. Over long periods the large majority of active managers underperform the index they are measured against, after fees.
The unglamorous consequence: for most people, most of the time, a low-cost global index fund is the correct default, and any deviation from it needs to justify itself.