Countability

Here is the list of posts on places where countability matters in topology, so far:

1. On countability
2. On countability: the compact completed sequence
3. Core-compact+well-filtered T₀ = sober locally compact
4. The Rasiowa-Sikorski lemma and the Baire property
5. Quasi-Polish spaces as rounded ideal completions
6. The Sorgenfrey line is not consonant
7. First-countable spaces and their Smyth powerdomain
8. On products of dcpos, the Miao-Xi-Li-Zhao lemma, and the complete lattice Lfan (part I)
9. When do products distribute over colimits in Top?

— Jean Goubault-Larrecq