Demo and coding parties are events where people with demo scene-related skills (from coding, pushing pixels, and composing tunes to simply drinking beer) meet to watch and celebrate their new creations. If you have one of these skills but have never been to a demoparty, I recommend you change that. Typically demo parties are held on a yearly schedule at the same place. 

Party Month Location Releases Visited / Link to Pictures
Evoke August Germany - Cologne Link 2010
Forever March / April Slovakia - Horná Súča Link not yet
Fujiama August Germany - Lengenfeld Link 2010, 201120122013, 2015, 2017, 2018, 2019, 2021, 2022, 2023
H.A.T.Z. April / May / June Germany - Hochstetten - Dhaun Link 2016, 2019, 2023
HomeCon Several Germany - Hanau n/a 2010, 2022
Outline May Netherlands - Willemsoord Link 2018
Revision Eastern Germany - Saarbrücken Link 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018
Silly Venture November / December Poland - Gdansk Link 2013, 2014, 2016, 2017, 2018, 2019, 2021, 2022, 2023 (planned)
tUM - The Ultimate Meeting December Germany - Darmstadt Link 2010, 2013