What is the Elder and purpose

Strong's concordance: elder, usually used as subst.; an elder, a member of the Sanhedrin, an elder of a Christian assembly.  It is important to know that elder is not in age.  It is in spiritual maturity.  I John 2:12-14 talks about 4 stages of spiritual maturity.

I John 2:12-14 says,

I write unto you, little children, because your sins are forgiven you for his name's sake.  I write unto you, fathers, because ye have known him that is from the beginning. I write unto you, young men, because ye have overcome the wicked one. I write unto you, little children, because ye have known the Father.  I have written unto you, fathers, because ye have known him that is from the beginning. I have written unto you, young men, because ye are strong, and the word of God abideth in you, and ye have overcome the wicked one.

Maturity is skill in the word of righteousness.  The elder was one that they appoint in the city in the ancient history of Christianity in Epistles.  They would assist in correspondence communication for Christians in every city.  There was not places that they came to meet.  Ecclesia means called out ones.  The epistles were written to the called out ones in Corinth, Ephesus or Galatia.  The elders would stand in front of the lambs to point them to Christ.  Sheep know Jesus and follow the voice of Jesus.