Online earnings from sites like ISC, blogging, advertisement, adsense etc are treated as income as far as the tax authorities are concerned (except honorary work without any income). In simple terms this fixed or variable money that comes into any account in our name or joint accounts would be tracked by the IT department.
The earnings that you get from all the online activities should be clubbed under Gross Income under the others section of the ITR
(ISC + Google adsense + online suverys, online blogs, personal site etc).
From this gross amount you can have deductions in part for example
depreciation of your laptop or desktop, camera,
internet expenses, telephone bill, electricity expenses and other day to day expenditure that you incur while you earn online.
If you have a sizeable earnings from online means and have an office, a few staff etc, you can list these expenses also.
If you are a professional blogger and some money on contracts, registration fees for other sites or even meet a potential client related to the online business, even this can be used for tax exemption. The amount of deduction/depreciation varies and is also influenced on other earnings and the slab under which you come under. It is better to at least once consult a tax consultant.
domain hosting, patent charges, website designing all can be shown as expenses.
Now for every financial year, you can deduct these from the gross amount and the remain can still be checked whether it can be offset by an unused quota of investment/donation and other exemptions. So, any money rupees or dollars or pounds that trickles into your account needs to be treated as taxable income and declared to avoid potential issues.