Webcomics have been around since the internet and web browsers were made public, the earliest i could find was Netboy a comedy comic running from may of 1994. Webcomics are self-published comics but hosted on the internet or mobile apps and due to the ease of publishing them there are millions made of ranging genres, popularity and quality.
Webcomics are by far the most popular type of indie comics made nowadays, though there are also webcomic focused publishers such as WEBTOON a korean company.
Researching webtoons I have found that there are thousands of different topics I could cover, periods in both the west and east, trends, popular webcomics, etc.
I chose to focus primarily on the comics themselves, the way they are formatted and the community that has been formed around the niche media.

Focusing on format in the early days webcomics were mostly inspired by the newspaper style of comicstrips, with a focus on humour relating to technology due to the internet at the time only really used by tech enthusiasts. Kevin and Kell, stated to be the longest running webcomic, was started in 1995 and was formatted though not focused on technology humour and instead the furry fandom. Formats changed by the mid 2000s as web designers who were also artists would use formats for their comics only possible on the internet, such as Andrew Hussie (Creator of Homestuck) who would format his comics like a web game with the use of software like flash.
In the east it became popular to structure webcomics via scrolling down; this could be used to transfer traditional comic structure, such as anticipation of page turns, to a web-only format. Nowadays this is the go to style for many full time webcomic artists as smartphones are extremely effective for reading this style of comic. Webcomics have the added benefits of being able to play multimedia such as the flash games mentioned before but also sounds, music and gifs. Horang, a korean horror webcomic artist used this to add jump scare to his works as scrolling down onto a panel would play a gif and a sound to scare the reader, which made him viral for many of his comics. Due to this it has been a nightmare for certain companies and creators to try and print webcomics into physical media, Homestuck being probably the best example as it was incredibly multimedia, most webcomics never get physically released but may get adapted into cartoons and anime. However in the 90s to early 2000s some would get cd-roms created for them since not everyone had internet connections back then, but using a rom they could display the webcomics on the computer, though this was also done with mainstream comics. Formats are probably the most undervalued aspects of webcomics as many, such as popular Korean webtoons, don’t take advantage of the multimedia aspects and only focus on the scrolling format.

Following up on that Korean webcomic history is way more interesting then the west, in the west it was scene as just another form of comic publishing or a way to make strange avant-garde art, but in korea it was one of the best ways to get comics published as comics were scrutinized in korea. In the 90s Korea saw comics as addictive and corrupting to the masses so they were heavily sanctioned and censored making it incredibly hard to be a comic artist in Korea, this led to Korean artist leaving to work in Japan but the emergence of the internet led to a boom in Korean webtoons. Since it was one of the only ways to get comics for korean youths and comic enthusiasts, as well as the internet being well developed in Korea before most of the world, Webcomics were more mainstream then print comics. Though much of the early history was unknown the idea of tall scrolling webcomics were mainstream by 2002. Though with the development of other countries and their ability of getting the internet each country had different topics and tropes for their comics, such as France with the “Blog BD” which were personal blogs telling stories of their lives instead of fictional stories. Finland also is surprisingly huge when it comes to webcomics produced, likely due to the fact connection to the internet is a lawful right there, though they followed the tropes of the west more with comedy comics.

Taking the focus off of countries, many cultural groups quickly created their own cliques around the internet, most famous of which would probably be the furry fandom. The furry fandom itself has had a long history with Indie comics, it could be said that the furry fandom actually started from the indie comic trend of anthropomorphic animals in the 60s and it kept that indie comic spirit going into the dot.com era. For a long time anthropomorphic characters were a common sight in english-speaking webcomics, but each furry comic could vary incredibly as the furry fandom tended to cross over with other fandoms. To this day furry webcomics are commonplace in western comics, especially in the self-publishing indie webcomic scene. Another group that rose at this time was the western anime fan, the early 2000s had a lot of young western artists who grew up watching the recently popular anime medium from Japan and wanted to draw inspired from their favorite shows. Ninjas, Samurais and spikey hair were sights everywhere on the internet, though mocked now it was influential in the style of webcomics because unlike american mainstream comics which all had a somewhat uniform look western artists would now experiment with the stylized look of manga. Nowadays a vast majority of western english-speaking comics have some anime influences in their art, sometimes even being fully drawn in an manga-inspired style. The two of these fandoms also crossed over since they both originated pre-internet in the same clique, furry fandom were the main consumers of anime before the 90s.
Though I should mention mainstream comic publishers and artists didn’t ignore webcomics, nowadays Marvel and DC have made web-exclusive comics quite common and in the 90s Todd Mcfarlane, founder of image comics, was incredibly invested in the scene.
It should be noted that the information I found really only focused on English-speaking, Korean and Japanese webcomics but other countries of course developed and were popular in their own countries, but there's a lack of information about them online.

Covering influential webcomics themselves I'll focus on a few, starting with Sonichu which is a very hard one to talk about quickly. Sonichu was a comic by Chris-Chan, an infamous figure on the internet, their comic was an interesting insight to how internet culture was formed. Briefly talking about Chris-Chan they are a very divisive figure who has done some objectively awful things but were also a victim of online harassment making talking about them very hard since the situation is grey. The Sonichu comic was influenced by this online harassment and Chris Chan was one of the first internet memes, the comic itself isn’t very good, it's a jumbled mess of one-note characters and copyright infringement drawn in a hard to decipher way. It’s probably one of the most famous webcomics however. Though Homestuck is the most famous webcomic ever, I briefly talked about it before so I'll just discuss its effects and fandom. Homestuck was the first webcomic to get a really big fandom due to the troll race in the comic, fan made troll characters were popular which led to big cosplay groups in the early 2010s as well as thousands of fanworks, Homestuck is the biggest success story of its time when it came to webcomics and many people who worked on it are still big on the internet today. Penny arcade is probably best to finish on as it's just as successful as Homestuck but incredibly early on in webcomic history. Penny Arcade also should be noted as the first webcomic ever able to bring in enough profit for the creators to live just making the comics, it also had led to multimedia such as animations, films, charity organizations and physical merchandise.

Webcomics nowadays are indie comics since it's much easier to self-publish online then it is to do with print media. Many young artists start and stay creating webcomics though there is still an idea that webcomics are a stepping stone to mainstream comics which will probably never go away. Webcomics in general are great to read since there's so much variety and cultural differences in ones made by foreigners. Though the independent webcomics aren't the only webcomics publishers like Line Webtoons and Tapas have been funding and publishing online comics for close to a decade now and some of the comics from these web publishers have more views then mainstream comic publishers especially with younger readers. The webcomics industry is likely to have another boom in a few years due to the surge in manhwa popularity in the west and animated adaptations of line webtoon properties. This might lead to indie comics becoming rarer on the internet much like how marvel and DC dominated the print comic industry, though i believe that culturally webcomics still have the independent creativity of indie comics as its main focus even in the mainstream webcomics nowadays.