Unemployment rate
The unemployment rate is the share of the labour force without a job and actively looking for one. It is a key indicator for central banks.
In the US, it is published in the same report as NFP, but it comes from a different survey, of households. In the eurozone, Eurostat publishes it every month, and in the UK, the ONS.
For the Fed, which has a dual mandate (price stability and maximum employment), a marked rise in unemployment can justify rate cuts. A very tight labour market, with low unemployment and strong wage growth, fuels inflation fears instead.
A 0.1-point change can move the market if it surprises. Look at the trend over several months rather than a single print.