What Do The Words In Blue Underlined Mean?

We see these daily and often not think about the what they are. They help is find a link to some where else, they are hidden right in front of us. Words like:
Machine Doubling, DDO, DDR, PMD, PSD, Feeder Finger Damage, Indian Head cent, Struck Through Grease, Grease Fill, Greaser, Jefferson nickel, CoopHome, Eisenhower dollar, Close AM, Wide AM, Jefferson nickel, Memorial cent, Wheat cent, Coop (all members names on their avatars and on the post creators column, link to their information page) All these and a lot more. So when we see these with the blue letters that are underlined, they are there to help us fill in the blanks. But new ones need this information from time to time and then they figure it out. But I thought I would create a blue line to show they are there to help when we need assistance. Kind of an answer that was not thought of yet, by our coin brothers and sisters.