The current structure formation model of Lambda Cold Dark Matter has been successful in explaining many observational results mainly from galaxy redshift surveys. However, there are still some remaining issues including the missing satellite problem and H_0 tension. 

I will first discuss dark galaxies, composed mostly of dark matter with little or no stars, which can be important tools for understanding the missing satellite problem. I will then discuss a new redshift survey, the All-sky Spectroscopic Survey (A-SPEC), which helps to understand the H_0 tension. I emphasise the power of combining observations from different wavelengths with cosmological simulations.