The network of regional and local buses in the Netherlands is fine-grained and frequent and usually connects well with the train network; you can reach most small villages easily. However, for long-distance travel, these regional buses are not convenient at all, and are much slower than the train.
Fast long-distance buses are only available on a small number of routes that aren’t covered by the rail network; these buses have special names that differ by region, such as Q-liner, Brabantliner and Interliner, and special tariffs.
There are four main bus companies in the Netherlands, Connexxion, Veolia, Arriva and Qbuzz. A few large cities have their own bus company.
A cheap way to get across the Netherlands is to buy a “buzzer” ticket. It costs €10 a day, and is valid after 9AM on every single Connexxion bus for two grownups and up to three children. On weekends and holidays it is also valid before 9AM. Because Connexxion has a near monopoly on the bus market, you can get from Groningen to Zeeland this way in a day, and it undercuts the train. A big downside though is that bus lines are very indirect. For example, if you want to travel from Amsterdam to Rotterdam, you have to change three or more times to get all the way there. In short: bus journeys will almost always take longer than train travel. For example, trip to Rotterdam from Utrecht will take 40 minutes, but in the Bus it will take 1 hour and 30 minutes. However, if you want to enjoy the countryside and villages you can prefer the bus trips.
Many companies and regions have their own bus discount tickets, which are often cheaper than using credit on the OV-chipkaart.
Park-and-ride-(travel-)tickets: some towns and cities have special cheaper bus tickets from car parks near the city limits to the city centre, for outside rush hours, usually a return ticket.
Amsterdam, Rotterdam, The Hague, Utrecht offer public transport at night. Only Amsterdam has a service all night and every night; in the other cities it is more limited to the beginning of the night or only during the weekend. Several other cities and regions also have night buses, usually even more limited.
You might need special night-bus tickets so be sure to check the city pages.