Google Scholar Citations is a citation service provided free of charge. It is easy to set up, especially if you already have a Google account.
The profile itself shows your list of publications in Google Scholar with basic metrics.Google Scholar covers a much broader in scope: includes more than a traditional database including book chapters, posters, abstracts, patents, technical reports, and content submitted to institutional repositories.
See Google's FAQ for answers on how to add missing publications or correct other errors.
Remember that the Google Scholar database does not have set inclusion parameters (e.g. journals, date ranges). Researchers should regularly check their own profile for duplicates, omissions and errors.
Citation counts and indices should not be compared between disciplines. For best results use multiple tools.
H-Index is the largest number h such that h publications have at least h citations. The second column has the "recent" version of this metric which is the largest number h such that h publications have at least h new citations in the last 5 years.
i10-Index is the number of publications with at least 10 citations. The second column has the "recent" version of this metric which is the number of publications that have received at least 10 new citations in the last 5 years.