keep track -
keep informed of fully aware; "I keep track of the stock market developments"
lose track fail to keep informed or aware; "She has so many books, she just lost track and cannot find this volume"
cognise,
cognize,
know be familiar or acquainted with a person or an object; "She doesn't know this composer"; "Do you know my sister?"; "We know this movie"; "I know him under a different name"; "This flower is known as a Peruvian Lily"
