First released on August 2, 1909. Designed by Victor David Brenner. His initials were on the reverse but were soon discontinued with those initials. In 1943 zinc coated steel replaced copper due to the WWII copper shortage. The Philadelphia, Denver, and San Antonio mints all produced the coins, but not in all years. Produced by the billions, these coins are plentiful today, certain varieties although are scarce. As a rule 1909 through 1914 are well struck, from 1915 through the 1920's are weak. Denver mint being particularly weak with many die pairs used over a long period of time striking qualities vary. Coins struck from overused or worn dies can have a grainy or even slightly wavy fields on either side, it's good to avoid these.
Cents of the first year 1909, are easily found in mint state after which they become scarce, Philadelphia varieties were made in higher qualities and more often seen. There are a number of rare and scarce varieties. In the 1930's collectors retrieved many earlier coins from circulation with typical grades for the key 1909 VDB and 1914 being fine or so. By the late 50's most early date coins were apt to be worn down to GF. The demand is great for scarcer types, thus keeping the market strong. Many early cents have be en dipped and recolored, particularly true of RD listed pieces. To assemble a truly choice collection, well struck of Lincoln cents of the 1910-1929 years takes a lot of patience.
* As always, I reference the book “Grading Coins by Photographs” by Q. David Bowers.