ASBA stands for Applications Supported by Blocked Amount.
It is process created by the SEBI and applies to IPOs, FPS, Rights Issues, etc. With the ASBA method, an IPO applicant’s bank account isn’t debited until shares are assigned. While subscribing for an issue via ASBA, your application money will get blocked within your back account. The blocked amount will only be debited if your application is chosen for the allotment. If the issue fails or is withdrawn, your amount will get unblocked. You can also submit your applications through Self Certified Syndicate Banks (SCSBs). The list of SCSBs can be found on SEBI's website. There are currently around 60 such banks.