S. Pit Corder's 1967 article entitled "The significance of learners' errors" is often cited as the starting point for the discipline now known as second language acquisition (SLA). This article discusses four major insights developed by Corder and explains how Corder's thinking has influenced the following lines of subsequent SLA research:
1. studies of learner errors
2. studies of L1 influence on SLA
3. studies of corrective feedback

Cultural keywords are words that reflect cultural values, beliefs, and history. Such words are often very difficult to translate in another language and the translator has to explicitly render them by including footnotes, or explanations in parentheses, or by using the technique of adaptation to find corresponding terms in the foreign language that would evoke the same feelings in the target audience. Cultural keywords constitute a challenge which requires experience on the translator's part, patience, and a profound knowledge of the culture of the source and target languages. In this review some examples from the Greek language are presented.

This case study in relation to the research conducted by linguists in second language acquisition, shows that there is no critical period for vocabulary, syntax and grammar, but that there is a critical period for phonological skills. This period is different among individuals, and is determined by several factors, such as motivation, repetition, encouragement, and shared phonological features between one’s first and second language.