so I been getting more and more into D&D and as I did I noticed I have been role playing elf's wrong! Alot of it has to do the trace feature and what it actually means!
so lets get too it! the trance is not just a great feature for playing the game but also for lore! using trace a elf foregoes sleeping (that being said elf's can sleep and dream! though they avoid doing so as dreams are a strange and bizarre thing to them!) during the trance they reflect on what happened in the past day allowing them to relive any and all events that day in vivid detail! but when elf's are younger this works differently and will change player perspective how elf's view things like life, death and family.
So when a elf is born, the elf is given a child name witch is temporary name given to them so people can call them something and for the most part the child is raised by all the other elf's around it in place of just its biological parents, when the young elf is old enough to learn how to go into a trance they see beautiful colors and random nonsense at first, that being said I think other elf's just teach the child this and other basics. Once the elf starts to mature more they start to get visions of there past life, detailed visions of there past life! see when a elf dies they reincarnate so a elf never really truly dies, they just move on to another mortal body and after one point they get back ALL there memories from ALL there past lives. So dying for a elf is not dying is more like NG+!
moving on when a elf gets there memories back they pick there adult name and carry there old clan name once more, when a elf dyes no other elf around it feels remorse as they know at one point in this life or the next they will encounter there old friend and clan again. now with all that being said, Drow do not have the same experience as other elf's there trance do not bring them visions of there past lives, they only see darkness so a drow's view on life and death is much much different than other types of elf's!

So remember next time you make a elf, your character has thousands of years of knowledge behind them! On top of that because of there ability to reincarnate death is kind of like the flu, you get better! Elf's in D&D are kind of like Time Lords...oh you died? just give them a few years they will be back in a shinny new body!
with this in mind a assassinating a elf is next to pointless (unless its a drow) as they will just reincarnate and start over where they left off and with all this in mind, if your running a elf and you DM asks for a history check for something in common knowledge and your DM doesn't just give it to you or at least advantage you have to ask...has your elf been living under a rock for the past few thousand years? Also when playing as a elf you might view other races as young regardless of what age they are, see that human, he is only 98 years old! hes still a baby! it is a fun experience to know you are the oldest person in the group by far. And if your a lawful good character you may throw yourself in the way to aid others more often than most, after all if you die its not your end but it may be the end for the other person! furthermore if your character dyes maybe you left something in your will for your friends to bring back to your clan so you may have it again in your next life! there is lots of  little hooks elf's can add!

Doing it wrong?

You do realize that you have your lore wrong (at least for the Forgotten Realms).  According to Mornenkainen's Tome of Foes (pg. 38), "the memories evoked during trance are drawn not from current life experiences, but from the fantastic past adventures of the elf's immortal soul. Parents of young elves and priests of Erevan Ilesere encourage the youths to explore these memories and talk about them with one another, but they aren't to be discussed with adults until a memory of waking life first intrudes upon a youngster's trance.  This experience, called the First Reflection, marks the end of childhood and the start of adolescence.  Most elves experience their First Reflection in their second or third decade.  It marks the beginning of the period when an elf must focus on acquiring the knowledge and skills needed for the elf's role as an adult.  As a means to this end, elves in adolescence learn how to use trance to evoke memories of their waking lives, giving them opportunities to reflect on the joys of the mortal world and to reinforce the principles of any training or practice undertaken while awake.  At the same time, the memories of long ago that came so easily during childhood now arise less and less frequently.  The Drawing of the Veil is the name that elves give to the occasion when a young elf no longer experiences primal memories during trance but instead recalls only the events of its current mortal existence."  

This section says that they lose the ability to recall memories from their past life once they reach adulthood, and that they have to learn from their past memories before hand.  They also focus on training and skills, and not past events, so unless the child was curious about their past life events (other than their training), they wouldn't be focusing on that.  Meaning that you cannot just go into a trance and get the answer to a history question unless it's something that your character would have been interested in and looked at it during a trance during childhood.  So your argument on having the knowledge or have advantage on the check is invalid.  Also you can't say that you would have the skills of a 20th level character when you reach adulthood either since you haven't actually worked on the ability.  You would have the knowledge and the memories of practice, but until you actually hone your body and mind to do the ability you can't perform it effectively.  

As for that they would take more risks because of their immortal soul, and they would be reincarnated, is also flawed.  Yes their soul is immortal but they don't know when they would be reincarnated, so they wouldn't just throw their current lives out the window unless they had justification to do so. 

Drow lore in the book doesn't say anything as to what you said, but I will say that it would be a different experience than other elves due to not worshiping the elven deities.  Whether or not they go through something similar or it's what you said and they only see darkness, I cannot say.

You need to make sure you have your facts right when you try to post something like this.  Also you never said how people were playing them wrong.  Is it that you believe that people are playing them wrong because they just don't throw caution to the wind and throw their lives away?  Or is it something else?  Everybody plays differently, and wants something different from everybody else.  Yes there is lore, but when you try to abuse that lore, you will get people upset.  This is a game and it should be fun for everybody and they play how they interpret what they read.  

You do know after the elf receives all there old memories the trance let's them reflect on there day, also time is next to meaningless to elfs so the about of time they stay dead is a huge deal to them!

All my facts are right you just interpreted them wrong, you do know there are more sources for the lore other than the books and sometimes the lore in the books clash with lore from other books! Next time before saying someone else is wrong you should at least check a few of the wikis! There are a ton of cases of elfs putting themselves in harm's way to aid other!

It feels pretty aggressive coming in and announcing that a lot of players are role playing wrong. You're entitled to your opinion, of course, but maybe a friendlier delivery would be better received.

That's the beautiful thing about individual games... you can run the lore for your elves any way you want. If that differs from how another DM runs it in his game, so be it. It's the diversity in D&D that makes the game so fun!

Your opinion becomes less well received when you don't use proper punctuation, don't capitalize your sentences, spell the ability you are talking about wrong consistently, and have worse than average grammar.

And then you start attacking the way people play their characters.

Poor form.

I get that there are other lore out there but I'm going based off of what is printed, which is now the official lore for the Forgotten Realms.  Wikis aren't official lore due to anybody can add too or take away from them.  I'll also admit that lore has changed over the editions and what once was lore for 3rd is not necessarily lore for 4th and so on.  I also stated based on what I have read this was the lore (again in the Forgotten Realms).  I also never said that elves never put themselves in the way of danger to help others.  Unless they believe their sacrifice would actually be of use, nobody would waste their life.  Wikis aren't the end all be all answer to the world of DnD.  Also notice how I provided a source for my information?  That's how you post facts on something.  Lore is ever changing and when they come out with a 6th edition, I'm sure the lore will have changed once again. 

It's also hard to argue with somebody that can't seem to use proper grammar.  I'm not going to say that my grammar is the best, but at least I know the difference of there, their, and they're.  When making a point, sounding at least semi educated goes a long way.  I will never say that I'm completely right.  How you worded your first post makes it sound like you are trying to get advantage on a check that you shouldn't.  No where, that I found at least, says that they see their entire past lives.  Their only goal is to learn from them so they know how to live.  It's hard to take in thousands of years of history in just a few decades.  It also doesn't say that they retain all the memories, just that they see them and can reflect on them to learn.  It's not like, oh I now have all these memories of my past lives now and I'm now the most knowledgeable being in existence.  

Wikis are good for stuff that hasn't been touched on in 5th edition, such as more information on city watch, city guard, and so forth for Dragonheist.  If you are playing 5th edition, official release material is what is cannon, and not wiki.  If it fits a person's character, their elf could be the very first elf that was ever created, or their elf could have the life span of a human.  The beauty of this game is that it's meant to make it your own (mainly the DM's).  Your DM (or yourself if you are the DM) can say that what you said is cannon for their world, or they can say that this lore doesn't fit and they don't get visions of their past lives when they go into a trance when they were a child.  I all ways like to look at it as the DM is the supreme god of the world.  He has final say on what is and isn't allowed in game, and what is and isn't lore.  

You never say that somebody is playing a character wrong.  It's their character and it's how they want to play it.  A lot of people don't care about lore, and only care about the racial features and stats, while others do care and look into the lore and play based on it.

In the end it's a game and it's meant to be fun.  I just don't like people who try to find loopholes in lore so they can get advantage on one thing or another.  If they had access to their past lives, they then would have proficiency in history as a racial trait.

Quote from WeldingBear >>

You never say that somebody is playing a character wrong.  It's their character and it's how they want to play it.

 Um... you do realize that the same goes for how a Gamemaster runs a game, don't you?

I believe I said something along those lines right above it, how the DM is the supreme god of the world and what they say goes.  But, yes, it's their game and you don't tell other people they are running their game wrong as well.  A DM decides what is lore for their world, which in turn dictates how certain races act and the like, but there are always exceptions to the rule.  Take Drizzt, who is a drow who are known to be evil, but Drizzt is good and goes against other drow.  Proxy's point only tries to point out that elves may have knowledge on something because of their past lives and that he wants advantage on a roll.  He makes the mistake of saying that an elf could just go into a trance and search their memories for an answer even though that is not how it works.  

The only time somebody can be wrong is if it's rule base and even then the DM can make a rule that contradicts a rule in the books since it's their world and what they say is law, is law.  I also state that I'm not all ways right and I get things wrong.  I should also add that I also forget about things in the heat of the moment.  I was ranting mostly because he thinks that wiki pages are the only lore, even though they're not official lore that is published at this time.  If he wants to go back to previous editions in lore then he should say so.  

This is also only my take on this matter.  There are many opinions out there and mine may not be the best one for some.