I use t3.micro instance and in its details "it is free tier :true /free trial available :false"

Hello.

I think "it is free tier :true" refers to the free tier for 12 months after creating an AWS account.
In regions where only "t3.micro" can be used, "t3.micro" can be used free of charge for 750 hours per month for 12 months.
https://aws.amazon.com/free/?nc1=h_ls&all-free-tier.sort-by=item.additionalFields.SortRank&all-free-tier.sort-order=asc&awsf.Free%20Tier%20Types=tier%2312monthsfree&awsf.Free%20Tier%20Categories=*all

I think "free trial available :false" is a trial with a limited time, such as 2 months free.
https://aws.amazon.com/free/?nc1=h_ls&all-free-tier.sort-by=item.additionalFields.SortRank&all-free-tier.sort-order=asc&awsf.Free%20Tier%20Types=tier%23trial&awsf.Free%20Tier%20Categories=*all

I think "t4g.small" is included in this trial.
https://aws.amazon.com/ec2/instance-types/t4/?nc1=h_ls

Free Trial: Try Amazon EC2 t4g.small instances powered by AWS Graviton2 processors free for up to 750 hours / month until Dec 31st 2024. Refer to the FAQ for additional details.

Hello Sayed Ismail,

Thanks for detail Info. As per the AWS Documentation EC2 t3.micro is not a free tier instance. You will be charged $0.0104 per hour. You can see more In detail in the following document.

https://aws.amazon.com/ec2/instance-types/t3/