Origin
The TIPI was created by Gosling, Rentfrow and Swann (2003) as a very brief measure of the Big Five personality dimensions — Openness, Conscientiousness, Extraversion, Agreeableness, and Emotional Stability (the inverse of Neuroticism). It was designed for research settings where the full Big Five inventories (44-240 items) are impractical, such as time-limited surveys or studies where personality is not the primary focus.
Structure
The TIPI uses ten items — two per dimension, each a pair of trait descriptors (one typical, one reverse-keyed) rated on a 7-point scale. This 2-items-per-trait design is deliberate: the authors argue that for broad domains, a small number of carefully chosen descriptors can capture the core of each dimension.
Psychometric standing
Because Cronbach's alpha penalises scales with few items and content breadth, Gosling et al. (2003) explicitly evaluated the TIPI using test-retest reliability and convergence with longer instruments (the Big Five Inventory and NEO-PI-R) rather than internal consistency.
On those criteria the TIPI performs well as a brief proxy: it reaches reasonable test-retest stability and converges with full-length measures. The authors are candid that the TIPI sacrifices some reliability and the ability to measure facets in exchange for extreme brevity, and recommend longer instruments when personality is the central variable.