If you were to get involved in a coffee-table discussion on OKRs, this brief summary will come to your rescue.
OKR framework recommends setting up 3-4 objectives at individual, team and company levels using S.M.A.R.T principle i.e. set goals that are – Specific, Measurable, Actionable, Relevant, Time-bound.
Each objective has 3-4 quantifiable key results that unambiguously define success/failure of the objective. This way every individual is aware of what is expected of her (the objective), how the success & failure is measured (the key results) & how it will help her team and ultimately company in fulfilling top level objectives. Aligning these different levels of objectives is a key aspect of OKR goal setting.
OKR assessments are typically done monthly or quarterly depending on various factors such as company stage, time spent by the employee in the company, importance of the OKRs involved etc. e.g. for newer employees it could be monthly but at a senior level they are scheduled quarterly.
Note that progress updates are different from assessments, and are expected to be performed each week. This way all the OKRs are updated near real time to reflect changes in market landscape, business strategy & its execution.
Although OKRs were in existence & in use for quite some time, real increase in adoption happened post Rick Klau’s seminar at Google ventures. This video on YouTube is widely popular & can be an advantageous starting point for anyone who is new to OKRs.