Steam servers typically go down for routine maintenance every Tuesday, usually starting between 12 p.m. and 3 p.m. Pacific Time (around 3 p.m. to 6 p.m. PT is common for maintenance) and this maintenance usually lasts less than an hour. If the servers are down right now, it is likely due to this scheduled maintenance, which aims to avoid peak usage hours while having staff available to promptly address any issues. Unscheduled or emergency maintenance could last longer depending on the situation. Steam does not provide advanced notifications in the client for these downtimes, so users generally find out once they try to connect.
If Steam servers are down outside the usual maintenance window, it may be due to an urgent fix or other issues, and the downtime length can vary. Generally, Steam maintenance is brief and will likely be resolved soon during their typical Tuesday maintenance period.
