Izakaya are casual dining bar-eateries that serve small snack dishes alongside a selection of traditional Japanese alcoholic beverages. The word Izakaya is actually a compound word consisting of "i" (to stay) and "sakaya" (sake shop), indicating how izakaya originated from sake shops that allowed customers to sit on the premises to drink. Izakaya are sometimes called akachōchin (red lantern) colloquially , because these paper lanterns are traditionally found in front of an izakaya. Izakaya are a popular places to have an evening drink and the wide range of dishes that may be offered are perfectly suited to pair with beer, sake or Shochu. 
Tachinomiya, literally translated to 'Standing bar', are laid-back bars with high counters, where you stand up while imbibing tour beverage of choice. Tachinomiya service hardworking Japanese for a quick drink and a bite to eat on the way home (or on the way to another Tachinomiya). Drinks are typically cheap due to lower taxes on bars having no seats. Each Tachinomiya is unique, ranging from warehouse like to swanky and many even have karaoke available for patrons to sing the night away.
Both Izakaya and Tachinomiya are extremely social places and are likely your best chance to interact with genuine local people during a short stay in Japan.
Kampai!
