This IOI 2021 is another Online Competition due to the still ongoing COVID-19 pandemic.
However, this time IOI 2021 is a full IOI minus the onsite social components.
Here are the summary of changes compared to the previous online IOI 2020:

• IOI registration fee (of 200 Euro) will be collected in 2021 (e-Payment details has been sent by the IOI treasurer)
• There will be committee member elections (president: 1 position (3y), IC: 3 positions (3y+2y+1y), ISC: 2 positions (3y+1y), ITC: 1 position (3y))
  Please view the terms of IC/ISC/ITC members here
  IOI members who are interested to apply must fill in the appropriate nomination form as listed in GA 1 details above
• There are 5 General Assemblies (GAs) on 19, 22, 24, 25, and 28 June 2021 for team leaders and committees
  Note that contestants can already leave the local contest site(s) after 25 June 2021
• IOI conference returns as an online conference on 21 June 2021 night and is open to everyone involved in IOI 2021
• In place of (onsite) social days/excursions, we will have virtual Singapore tour instead

No changes compared to last year:

• Unfortunately, there is still no guest track and there is no onsite social day/excursion
  We hope that we can already return to in-person IOI by IOI 2022, hosted by Indonesia
• Registered adjuncts (local proctors and/or additional translators) do not need to pay any guest fee
• There is no live scoreboard
  Static result will be posted after each contest day
• There is no live stream (of the contests)
• There are only virtual opening and closing ceremonies using YouTube
  Participants can choose to watch them live together with the host
  However, participants can also watch the recording anytime afterwards