Time lines are diagrams used to represent the relationship between a verb tense and time, by showing what time - past, present or future - that tense covers.

Example :
Yesterday, I met Bob.

In the classroom
Time lines are one of many ways to talk about how verb tenses work. They are a visual representation, so they are useful for some learners with learning styles that respond to visual information. However, they can be confusing for others.

Further links: