Matt Bird writes all sorts of nonsense, but he dedicates a large chunk of his time to writing game walkthroughs.
Unless you are the best of the best among Dark Souls players - in which case you probably don't need this guide - upgrading your Estus Flask is an absolute necessity. You'll be taking a lot of damage in Dark Souls III, and every sip you get from your Estus Flask will make your journey a little easier. To upgrade it, you'll need Estus Shards, and they're not always easy to find.
This guide will lead you to all of the Estus Shards in Dark Souls III. You don't need to go too far out of your way to find them - but that doesn't mean you shouldn't be very, very careful in the process.
The first Estus Shard you can find in Dark Souls III is in Firelink itself, though you probably won't pick it up until you have a few areas under your belt. Speak to the Shrine Maiden and you'll see that she has a Tower Key for sale at the steep price of 20,000 souls. Purchase the Key, then head back towards Firelink's entrance and take the stairs to the left of the door leading outside. This leads up to an ominous-looking tree and a locked tower.
The Tower Key will open the tower. Climb up to find a pathway leading to another tower. Ignore this second climb for now and use the broken bits of wall on your left to fall down onto Firelink's roof. If you see a crow's nest, you're in the right place. You can drop down from the roof to a ringed pathway. Check the walls along this pathway for a doorway back into the shrine. You'll see crossed supports ahead, high above the rest of Firelink, and the Estus Shard is right in the middle of the supports.
(Want an extra prize? Once you have the Shard Shard, continue straight across the support and check the wall. It's an illusion, behind which you'll find a chest containing a Covetous Silver Serpent Ring. Score!)
High Wall of Lothric
During your trip to the High Wall of Lothric, you'll come to a branch in the path shortly after facing a Pus of Man on a rooftop, and you can either go down a ladder or into a building to face off against a Lothric Knight. If you opt to take the side path past the knight, you'll enter a large room with balconies overlooking a number of enemies. You'll find the first Estus Shard down among the enemies, sitting on an anvil. Using ranged attacks to draw your foes up to you is a wiser approach than leaping down among them and hoping for the best.
Just outside the first building you'll enter in the Undead Settlement, you'll see a burning tree surrounded by peasant Hollows, as well as a bulky, mace-wielding Evangelist. The Estus Shard is sitting near the base of the tree. You can either rush in, grab it, and run before anyone has much time to react, or you can move around the edges of the crowd and slowly pick everyone off. The Evangelist has a long reach with her mace so be wary of her as you take out her lesser mooks.
Road of Sacrifices
If you jump to the Crucifixion Woods bonfire, you'll have a path ahead that leads into a large, ruined building and up to the Crystal Sage boss fight. If you hug the dirt wall to your left, you'll pass a few spear-wielding Hollows, a summon sign for Holy Knight Hodrick, and a drop down to a campfire guarded by two crucifix-bound Lycanthropes. The Estus Shard is at the bottom of the drop that leads to the Lycanthropes.
Jump to the Farron Keep bonfire and you'll be facing a massive swamp with no obvious direction. Take a slight left from the bonfire, into the swamp, and you'll see the top of a tower sinking into the mire, watched over by Rotten Slugs. The Estus Shard is near this tower, in plain sight.
Cathedral of the Deep
Upon arrival at the Cleansing Chapel bonfire, you'll need to go back outside to access the graveyard that leads to the rest of the Cathedral of the Deep. Along this road, just outside the Chapel, is a small monument surrounded by praying Hollows. Kill the Hollows and check the item at the base of the monument for an Estus Shard.
Jump to the Old King's Antechamber bonfire. If you look in the opposite corner of the room, you'll find an illusory wall that you can smack out of your way, revealing a tunnel that leads back to one of the area's main thoroughfares. Take a left before you reach the end of this tunnel and run through the next passage, as its ceilings are lined with Smouldering Rotten Flesh blobs that will try to fall on your head. Look left at the end of the passage to see the Estus Shard, sitting in front of a pitfall.
Travel through Irithyll Dungeon until you get the Jailbreaker's Key, found in a cell across the bridge from the first bonfire. Head straight down the hall from the bonfire and the bridge until you find a locked door. The Key will get you through, dropping you onto an outer pathway leading to your right. Defeat the enemies along your way and enter the room that's dead ahead. Inside is a Mimic pretending to be a treasure chest. Kill it to get the Estus Shard.
Once you've opened the massive double doors of Anor Londo, head inside and hug the left wall. There's a small indent in the architecture, and sitting behind the third pillar, partially obscured by the darkness, is a treasure chest. Inside is the Estus Shard. You'll need to fend off a few Writhing Rotten Flesh blobs to get it.
Consumed King's Garden
Once you've defeated the Dancer of the Boreal Valley and triggered her bonfire, head up into Lothric Castle and take a left. You'll find an elevator down to the Consumed King's Garden, guarded by a Cathedral Knight. Kill or avoid the Knight, go down the elevator, and jump off the elevator before it reaches the bottom. You'll find a wooden platform and some stairs on your right. Go down the stairs to find the Estus Shard before dropping to ground level.
Proceed to the roof of Lothric Castle after making your way to the Grand Archives. Just before the long, enemy-filled bridge leading up to the Lothric Princes boss fight you can take a left and get up onto a domed roof. Explore the rear of this area to find a small archway leading to a balcony. There's a body with the final Estus Shard here. (Be careful - if you've claimed the Hunter's Ring above this area will be patrolled by Ascended Winged Knights, and they want your head.)