If you want the dictionary definition, just double click on any word.

Later is an adverb. It's used to express time, either in the future or after the time you have mentioned.

For example: "I'll see you later on Second Life."

Latter is an adjectiv, which means near or towards the end of something

For example: "I got tired during the latter part of the walk."

!Latter can also be used to describe the second thing of two things mentioned.

For example: Later, at the end of his apprenticeship, he was offered the choice of going to Russia for further experience in the flax trade or of entering a university he decided on the latter course and entered the University of Edinburgh in 1882 to study for the B.Sc. Degree in Physical Science.