Number of transactions
The number of transactions in a blockchain is the most important metric, since it shows the usage of the technology in everyday situations. Transactions represent activity. The more transactions, the more people actively using the blockchain for investing in projects, running dApps and using smart contracts.
It doesn't make sense to have billions of users if no one is using the technology; the more transactions there are, the more useful the technology is. You'll also see in the next heading that Ethereum is experiencing growing pains and is not being used as much as it should. People are joining it, but they are not using it enough. This is a huge concern in the community that must be surpassed to become mainstream.
When Ethereum started, there were 8,893 transactions, which then became 448,168 daily transactions on January 1st, 2019. The record was 1,349,890 on January 4th, 2018.
Here's a visual of the number of transactions since Ethereum was launched in 2015 for your reference:
The preceding screenshot tells us that 448 thousand daily transactions are coming from daily transfers, people using dApps, investors participating in ICOs, and people playing with smart contracts. In contrast, PayPal is handling 7.6 billion transactions per year as of December 2017, which is about 633 million transactions per day. PayPal is a mainstream technology used all over the world, so, for Ethereum to reach such level of mass adoption, it has to grow about 1,413 times its current level of transactions. This clearly indicates to us that Ethereum is still in its infancy and it will take several years, with the current usage, to become relevant at such a scale.
The chart reveals that Ethereum is not increasing the number of daily transactions since last year. This is usual in the blockchain space and is expected to continue growing after a while because of the many improvements that the technology is yet to experience.